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Radare2 Tutorial

how to use radare2

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0% found this document useful (0 votes)

768 views375 pages

Radare2 Tutorial

how to use radare2

Uploaded by

Sonu Sangwan

We take content rights seriously. If you suspect this is your content, claim it here.

Available Formats

Download as PDF, TXT or read online on Scribd

You are on page 1/ 375

Table

of Contents
Introduction 1.1
History 1.1.1
The Framework 1.1.2

Downloading radare2 1.1.3

Compilation and Portability 1.1.4

Compilation on Windows 1.1.5

User Interfaces 1.1.6

First Steps 1.2

Command-line Flags 1.2.1

Command Format 1.2.2

Expressions 1.2.3

Basic Debugger Session 1.2.4

Contributing to radare2 1.2.5

Configuration 1.3
Colors 1.3.1

Configuration Variables 1.3.2

Files 1.3.3
Basic Commands 1.4

Seeking 1.4.1
Block Size 1.4.2

Sections 1.4.3
Mapping Files 1.4.4
Print Modes 1.4.5

Flags 1.4.6
Write 1.4.7
Zoom 1.4.8

2
Yank/Paste 1.4.9

Comparing Bytes 1.4.10

SDB 1.4.11

Visual mode 1.5

Visual Disassembly 1.5.1

Visual Assembler 1.5.2

Visual Configuration Editor 1.5.3

Visual Panels 1.5.4

Searching bytes 1.6

Basic Searches 1.6.1

Configurating the Search 1.6.2

Pattern Search 1.6.3

Automation 1.6.4

Backward Search 1.6.5

Search in Assembly 1.6.6

Searching for AES Keys 1.6.7

Disassembling 1.7
Adding Metadata 1.7.1

ESIL 1.7.2
Analysis 1.8

Code Analysis 1.8.1

Variables 1.8.2
Types 1.8.3

Calling Conventions 1.8.4

Virtual Tables 1.8.5

Syscalls 1.8.6
Emulation 1.8.7

Symbols information 1.8.8

Signatures 1.8.9
Graph commands 1.8.10
3
Scripting 1.9

Loops 1.9.1
Macros 1.9.2

R2pipe 1.9.3
Debugger 1.10

Getting Started 1.10.1

Migration from ida, GDB or WinDBG 1.10.2

Registers 1.10.3
Memory Maps 1.10.4

Heap 1.10.5

Files 1.10.6

Reverse Debugging 1.10.7

Remote Access 1.11

Remote GDB 1.11.1

Remote WinDbg 1.11.2

Command Line Tools 1.12

Rax2 1.12.1
Rafind2 1.12.2

Rarun2 1.12.3
Rabin2 1.12.4

File Identification 1.12.4.1

Entrypoint 1.12.4.2
Imports 1.12.4.3

Exports 1.12.4.4
Symbols (exports) 1.12.4.5

Libraries 1.12.4.6
Strings 1.12.4.7

Program Sections 1.12.4.8

Radiff2 1.12.5
Binary Diffing 1.12.5.1
4
Rasm2 1.12.6

Assemble 1.12.6.1
Disassemble 1.12.6.2

Configuration 1.12.6.3
Ragg2 1.12.7

Language 1.12.7.1

Rahash2 1.12.8

Rahash Tool 1.12.8.1

Plugins 1.13

IO plugins 1.13.1

Asm plugins 1.13.2

Analysis plugins 1.13.3

Bin plugins 1.13.4

Other plugins 1.13.5

Python plugins 1.13.6

Debugging 1.13.7
Testing 1.13.8
Packaging 1.13.9

Crackmes 1.14
IOLI 1.14.1

IOLI 0x00 1.14.1.1

IOLI 0x01 1.14.1.2
Avatao 1.14.2

R3v3rs3 4 1.14.2.1
.intro 1.14.2.1.1

.radare2 1.14.2.1.2
.first_steps 1.14.2.1.3

.main 1.14.2.1.4
.vmloop 1.14.2.1.5
.instructionset 1.14.2.1.6
5
.bytecode 1.14.2.1.7

.outro 1.14.2.1.8
Reference Card 1.15

Acknowledgments 1.16

6
Introduction

Introduction
This book is an updated version (started by maijin) of the original radare1 book (written by pancake).
Which is actively maintained and updated by many contributors over the Internet.

Check the Github site to add new contents or fix typos:

Github: https://github.com/radare/radare2book
Gitbook: https://www.gitbook.com/book/radare/radare2book/details

Gitbook autogenerates HTML/PDF/EPUB/MOBIL versions in here:

Online: http://radare.gitbooks.io/radare2book/content/
PDF: https://www.gitbook.com/download/pdf/book/radare/radare2book
Epub: https://www.gitbook.com/download/epub/book/radare/radare2book
Mobi: https://www.gitbook.com/download/mobi/book/radare/radare2book

7
History

History
In 2006, Sergi Àlvarez (aka pancake) was working as a forensic analyst. Since he wasn't allowed to use
private software for his personal needs, he decided to write a small tool-a hexadecimal editor-with very
basic characteristics:

be extremely portable (unix friendly, command line, c, small)

open disk devices, this is using 64bit offsets
search for a string or hexpair
review and dump the results to disk

The editor was originally designed to recover a deleted file from an HFS+ partition.

After that, pancake decided to extend the tool to have a pluggable io to be able to attach to processes
and implemented the debugger functionalities, support for multiple architectures, and code analysis.

Since then, the project has evolved to provide a complete framework for analyzing binaries, while
making use of basic UNIX concepts. Those concepts include the famous "everything is a file", "small
programs that interact using stdin/stdout", and "keep it simple" paradigms.

The need for scripting showed the fragility of the initial design: a monolithic tool made the API hard to
use, and so a deep refactoring was needed. In 2009 radare2 (r2) was born as a fork of radare1. The
refactor added flexibility and dynamic features. This enabled much better integration, paving the way to
use r2 from different programming languages. Later on, the r2pipe API allowed access to radare2 via
pipes from any language.

What started as a one-man project, with some eventual contributions, gradually evolved into a big
community-based project around 2014. The number of users was growing fast, and the author-and main
developer-had to switch roles from coder to manager in order to integrate the work of the different
developers that were joining the project.

Instructing users to report their issues allows the project to define new directions to evolve in.
Everything is managed in radare2's GitHub and discussed in the Telegram channel.

The project remains active at the time of writing this book, and there are several side projects that
provide, among other things, a graphical user interface (Cutter), a decompiler (r2dec, radeco), Frida
integration (r2frida), Yara, Unicorn, Keystone, and many other projects indexed in the r2pm (the
radare2 package manager).

8
History

Since 2016, the community gathers once a year in r2con, a congress around radare2 that takes place in
Barcelona.

9
The Framework

The Framework
The Radare2 project is a set of small command-line utilities that can be used together or independently.

This chapter will give you a quick understanding of them, but you can check the dedicated sections for
each tool at the end of this book.

radare2
The main tool of the whole framework. It uses the core of the hexadecimal editor and debugger. radare2
allows you to open a number of input/output sources as if they were simple, plain files, including disks,
network connections, kernel drivers, processes under debugging, and so on.

It implements an advanced command line interface for moving around a file, analyzing data,
disassembling, binary patching, data comparison, searching, replacing, and visualizing. It can be
scripted with a variety of languages, including Python, Ruby, JavaScript, Lua, and Perl.

rabin2
A program to extract information from executable binaries, such as ELF, PE, Java CLASS, Mach-O,
plus any format supported by r2 plugins. rabin2 is used by the core to get data like exported symbols,
imports, file information, cross references (xrefs), library dependencies, and sections.

rasm2
A command line assembler and disassembler for multiple architectures (including Intel x86 and x86-64,
MIPS, ARM, PowerPC, Java, and myriad of others).

Examples

$ rasm2 -a java 'nop'

$ rasm2 -a x86 -d '90'

nop

10
The Framework

$ rasm2 -a x86 -b 32 'mov eax, 33'

b821000000

$ echo 'push eax;nop;nop' | rasm2 -f -

509090

rahash2
An implementation of a block-based hash tool. From small text strings to large disks, rahash2 supports
multiple algorithms, including MD4, MD5, CRC16, CRC32, SHA1, SHA256, and others. rahash2 can
be used to check the integrity or track changes of big files, memory dumps, or disks.

Examples

$ rahash2 file
file: 0x00000000-0x00000007 sha256: 887cfbd0d44aaff69f7bdbedebd282ec96191cce9d7fa7336298
a18efc3c7a5a

$ rahash2 file -a md5

file: 0x00000000-0x00000007 md5: d1833805515fc34b46c2b9de553f599d

radiff2
A binary diffing utility that implements multiple algorithms. It supports byte-level or delta diffing for
binary files, and code-analysis diffing to find changes in basic code blocks obtained from the radare
code analysis.

rafind2
A program to find byte patterns in files.

ragg2
A frontend for r_egg. ragg2 compiles programs written in a simple high-level language into tiny
binaries for x86, x86-64, and ARM.

11
The Framework

Examples

$ cat hi.r
/* hello world in r_egg */
write@syscall(4); //x64 write@syscall(1);
exit@syscall(1); //x64 exit@syscall(60);

main@global(128) {
.var0 = "hi!\n";
write(1,.var0, 4);
exit(0);
}
$ ragg2 -O -F hi.r
$ ./hi
hi!

$ cat hi.c
main@global(0,6) {
write(1, "Hello0", 6);
exit(0);
}
$ ragg2 hi.c
$ ./hi.c.bin
Hello

rarun2
A launcher for running programs within different environments, with different arguments, permissions,
directories, and overridden default file descriptors. rarun2 is useful for:

Solving crackmes
Fuzzing
Test suites

Sample rarun2 script

$ cat foo.rr2
#!/usr/bin/rarun2
program=./pp400
arg0=10
stdin=foo.txt
chdir=/tmp
#chroot=.
./foo.rr2

12
The Framework

Connecting a Program with a Socket

$ nc -l 9999
$ rarun2 program=/bin/ls connect=localhost:9999

Debugging a Program Redirecting the stdio into Another

Terminal
1 - open a new terminal and type 'tty' to get a terminal name:

$ tty ; clear ; sleep 999999

/dev/ttyS010

2 - Create a new file containing the following rarun2 profile named foo.rr2:

#!/usr/bin/rarun2
program=/bin/ls
stdio=/dev/ttys010

3 - Launch the following radare2 command:

r2 -r foo.rr2 -d /bin/ls

rax2
A minimalistic mathematical expression evaluator for the shell that is useful for making base
conversions between floating point values, hexadecimal representations, hexpair strings to ASCII, octal
to integer, and more. It also supports endianness settings and can be used as an interactive shell if no
arguments are given.

Examples

13
The Framework

$ rax2 1337
0x539

$ rax2 0x400000
4194304

$ rax2 -b 01111001
y

$ rax2 -S radare2
72616461726532

$ rax2 -s 617765736f6d65
awesome

14
Downloading radare2

Downloading radare2
You can get radare from the website, http://radare.org, or the GitHub repository:
https://github.com/radare/radare2

Binary packages are available for a number of operating systems (Ubuntu, Maemo, Gentoo, Windows,
iPhone, and so on). Yet, you are highly encouraged to get the source and compile it yourself to better
understand the dependencies, to make examples more accessible and of course to have the most recent
version.

A new stable release is typically published every month. Nightly tarballs are sometimes available at
http://bin.rada.re/.

The radare development repository is often more stable than the 'stable' releases. To obtain the latest
version:

$ git clone https://github.com/radare/radare2.git

This will probably take a while, so take a coffee break and continue reading this book.

To update your local copy of the repository, use git pull anywhere in the radare2 source code tree:

$ git pull

If you have local modifications of the source, you can revert them (and lose them!) with:

$ git reset --hard HEAD

Or send us a patch:

$ git diff > radare-foo.patch

The most common way to get r2 updated and installed system wide is by using:

$ sys/install.sh

Build with meson + ninja

15
Downloading radare2

There is also a work-in-progress support for Meson.

Using clang and ld.gold makes the build faster:

CC=clang LDFLAGS=-fuse-ld=gold meson . release --buildtype=release --prefix ~/.local/sto

w/radare2/release
ninja -C release
# ninja -C release install

Helper Scripts
Take a look at the sys/* scripts, those are used to automate stuff related to syncing, building and
installing r2 and its bindings.

The most important one is sys/install.sh . It will pull, clean, build and symstall r2 system wide.

Symstalling is the process of installing all the programs, libraries, documentation and data files using
symlinks instead of copying the files.

By default it will be installed in /usr, but you can define a new prefix as argument.

This is useful for developers, because it permits them to just run 'make' and try changes without having
to run make install again.

Cleaning Up
Cleaning up the source tree is important to avoid problems like linking to old objects files or not
updating objects after an ABI change.

The following commands may help you to get your git clone up to date:

$ git clean -xdf

$ git reset --hard @~10
$ git pull

If you want to remove previous installations from your system, you must run the following commands:

$ ./configure --prefix=/usr/local
$ make purge

16
Downloading radare2

17
Compilation and Portability

Compilation and Portability

Currently the core of radare2 can be compiled on many systems and architectures, but the main
development is done on GNU/Linux with GCC, and on MacOS X with clang. Radare is also known to
compile on many different systems and architectures (including TCC and SunStudio).

People often want to use radare as a debugger for reverse engineering. Currently, the debugger layer can
be used on Windows, GNU/Linux (Intel x86 and x86_64, MIPS, and ARM), OS X, FreeBSD, NetBSD,
and OpenBSD (Intel x86 and x86_64)..

Compared to core, the debugger feature is more restrictive portability-wise. If the debugger has not been
ported to your favorite platform, you can disable the debugger layer with the --without-debugger
configure script option when compiling radare2.

Note that there are I/O plugins that use GDB, GDB, WinDbg, or Wine as back-ends, and therefore rely
on presence of corresponding third-party tools (in case of remote debugging - just on the target
machine).

To build on a system using acr and GNU Make (e.g. on *BSD systems):

$ ./configure --prefix=/usr
$ gmake
$ sudo gmake install

There is also a simple script to do this automatically:

$ sys/install.sh

Static Build
You can build radare2 statically along with all other tools with the command:

$ sys/static.sh

Docker
Radare2 repository ships a Dockerfile that you can use with Docker.

18
Compilation and Portability

This dockerfile is also used by Remnux distribution from SANS, and is available on the docker
registryhub.

Cleaning Up Old Radare2 Installations

./configure --prefix=/old/r2/prefix/installation
make purge

19
Compilation on Windows

Windows
Radare2 relies on the Meson build system generator to support compilation on all platforms, including
Windows. Meson will generate a Visual Studio Solution, all the necessary project files, and wire up the
Microsoft Visual C++ compiler for you.

You can download nightly binaries from https://bin.rada.re.

Prerequisites
Visual Studio 2015 (or higher)
Python 3
Meson
Git

Step-by-Step

Install Visual Studio 2015 (or higher)

Visual Studio must be installed with a Visual C++ compiler, supporting C++ libraries, and the
appropriate Windows SDK for the target platform version.

In the Visual Studio 2015 installer, ensure Programming Languages > Visual C++ is selected
In the Visual Studio 2017+ installers, ensure the Desktop development with C++ workload is
selected

If you need a copy of Visual Studio, the Community versions are free and work great.

Download Visual Studio 2015 Community (registration required)

Download Visual Studio 2017 Community

Install Python 3 and Meson via Conda

It is strongly recommended you install Conda — a Python environment management system — when
working with Python on the Windows platform. This will isolate the Radare2 build environment from
other installed Python versions and minimize potential conflicts.
20
Compilation on Windows

Set Up Conda:

1. Download the appropriate Conda (Python 3.x) for your platform (https://conda.io/miniconda.html)
2. Install Conda with the recommended defaults

Create a Python Environment for Radare2

Follow these steps to create and activate a Conda environment named r2. All instructions from this
point on will assume this name matches your environment, but you may change this if desired.

1. Start > Anaconda Prompt

2. conda create -n r2 python=3

3. activate r2

Any time you wish to enter this environment, open the Anaconda Prompt and re-issue activate r2 .
Conversely, deactivate will leave the environment.

Install Meson

All versions of Meson at or below 0.47.1 have a bug that prevent normal use on Windows.
Because there's no official release with the fixes available, you must install from sources. The
following steps will walk you through this. We will update this documentation as soon as 0.48 is
officially released.

1. Enter the Radare2 Conda environment, if needed ( activate r2 )

2. Download https://github.com/mesonbuild/meson/archive/master.zip
3. pip install \path\to\downloaded\master.zip

4. Verify Meson is version 0.48 or higher ( meson -v )

Install Git for Windows

All Radare2 code is managed via the Git version control system and hosted on GitHub.

Follow these steps to install Git for Windows.

1. Download Git for Windows (https://git-scm.com/download/win)

As you navigate the install wizard, we recommend you set these options when they appear:

Use a TrueType font in all console windows

21
Compilation on Windows

Use Git from the Windows Command Prompt

Use the native Windows Secure Channel library (instead of OpenSSL)
Checkout Windows-style, commit Unix-style line endings (core.autocrlf=true)
Use Windows' default console window (instead of Mintty)
2. Close any previously open console windows and re-open them to ensure they receive the new
PATH

3. Ensure git --version works

Get Radare2 Code

Follow these steps to clone the Radare2 git repository.

1. In your Radare2 Conda environment, navigate to a location where the code will be saved and
compiled. This location needs approximately 3-4GiB of space
2. Clone the repository with git clone https://github.com/radare/radare2.git

Compile Radare2 Code

Follow these steps to compile a debug 32-bit (x86) version of Radare2. (If you want to build a 64-bit
(x64) version of Radare2, replace all instances of x86 with x64 . Similarly, if you want to build a
release version, replace all instances of debug with release .)

Compiled binaries will be installed into the dest folder.

1. Enter the Radare2 Conda environment

2. Navigate to the root of the Radare2 sources ( cd radare2 )
3. Initialize Visual Studio tooling by executing the command that matches the version of Visual
Studio installed on your machine:

Visual Studio 2015: "%ProgramFiles(x86)%\Microsoft Visual Studio

14.0\VC\vcvarsall.bat" x86

Visual Studio 2017: "%ProgramFiles(x86)%\Microsoft Visual

Studio\2017\Enterprise\VC\Auxiliary\Build\vcvars32.bat"

Visual Studio Preview: "%ProgramFiles(x86)%\Microsoft Visual

Studio\Preview\Enterprise\VC\Auxiliary\Build\vcvars32.bat"

4. Generate the build system with Meson: meson build --buildtype debug --backend vs2015 --
prefix %cd%\dest

22
Compilation on Windows

Meson currently requires --prefix to point to an absolute path. We use the %CD% pseudo-
variable to get the absolute path to the current working directory.

5. Start a build: msbuild build\radare2.sln /p:Configuration=Debug /m

The /m[axcpucount] switch creates one MSBuild worker process per logical processor on your
machine. You can specify a numeric value (e.g. /m:2 ) to limit the number of worker processes if
needed. (This should not be confused with the Visual C++ Compiler switch /MP .)

6. Install into your destination folder: meson install -C build --no-rebuild

7. Check your Radare2 version: dest\bin\radare2.exe -v

23
User Interfaces

User Interfaces
Radare2 has seen many different user interfaces being developed over the years.

Maintaining a GUI is far from the scope of developing the core machinery of a reverse engineering
toolkit: it is preferred to have a separate project and community, allowing both projects to collaborate
and to improve together - rather than forcing cli developers to think in gui problems and having to jump
back and forth between the graphic aspect and the low level logic of the implementations.

In the past, there have been at least 5 different native user interfaces (ragui, r2gui, gradare, r2net,
bokken) but none of them got enough maintenance power to take off and they all died.

In addition, r2 has an embedded webserver and ships some basic user interfaces written in html/js. You
can start them like this:

$ r2 -c=H /bin/ls

After 3 years of private development, Hugo Teso; the author of Bokken (python-gtk gui of r2) released
to the public another frontend of r2, this time written in c++ and qt, which has been very welcomed by
the community.

This GUI was named Iaito, but as long as he prefered not to keep maintaining it, Xarkes decided to fork
it under the name of Cutter (name voted by the community), and lead the project. This is how it looks:

https://github.com/radareorg/cutter.

24
User Interfaces

25
First Steps

Basic Radare2 Usage

The learning curve is usually somewhat steep at the beginning. Although after an hour of using it you
should easily understand how most things work, and how to combine the various tools radare offers.
You are encouraged to read the rest of this book to understand how some non-trivial things work, and to
ultimately improve your skills.

Navigation, inspection and modification of a loaded binary file is performed using three simple actions:
seek (to position), print (buffer), and alternate (write, append).

The 'seek' command is abbreviated as s and accepts an expression as its argument. The expression can
be something like 10 , +0x25 , or [0x100+ptr_table] . If you are working with block-based files,
you may prefer to set the block size to a required value with b command, and seek forward or
backwards with positions aligned to it. Use s++ and s-- commands to navigate this way.

If radare2 opens an executable file, by default it will open the file in Virtual Addressing (VA) mode and
the sections will be mapped to their virtual addresses. In VA mode, seeking is based on the virtual
address and the starting position is set to the entry point of the executable. Using -n option you can
suppress this default behavior and ask radare2 to open the file in non-VA mode for you. In non-VA
mode, seeking is based on the offset from the beginning of the file.

26
First Steps

The 'print' command is abbreviated as p and has a number of submodes — the second letter
specifying a desired print mode. Frequent variants include px to print in hexadecimal, and pd for
disassembling.

To be allowed to write files, specify the -w option to radare2 when opening a file. The w command
can be used to write strings, hexpairs ( x subcommand), or even assembly opcodes ( a subcommand).
Examples:

> w hello world ; string

> wx 90 90 90 90 ; hexpairs
> wa jmp 0x8048140 ; assemble
> wf inline.bin ; write contents of file

Appending a ? to a command will show its help message, for example, p? . Appending ?* will
show commands starting with the given string, e.g. p?* .

To enter visual mode, press V<enter> . Use q to quit visual mode and return to the prompt.

In visual mode you can use HJKL keys to navigate (left, down, up, and right, respectively). You can use
these keys in cursor mode toggled by c key. To select a byte range in cursor mode, hold down SHIFT
key, and press navigation keys HJKL to mark your selection.

While in visual mode, you can also overwrite bytes by pressing i . You can press TAB to switch
between the hex (middle) and string (right) columns. Pressing q inside the hex panel returns you to
visual mode. By pressing p or P you can scroll different visual mode representations. There is a
second most important visual mode - curses-like panels interface, accessible with V! command.

27
Command-line Flags

Command-line Options
The radare core accepts many flags from the command line.

This is an excerpt from the usage help message:

$ radare2 -h
Usage: r2 [-ACdfLMnNqStuvwzX] [-P patch] [-p prj] [-a arch] [-b bits] [-i file]
[-s addr] [-B baddr] [-m maddr] [-c cmd] [-e k=v] file|pid|-|--|=
-- run radare2 without opening any file
- same as 'r2 malloc://512'
= read file from stdin (use -i and -c to run cmds)
-= perform !=! command to run all commands remotely
-0 print \x00 after init and every command
-2 close stderr file descriptor (silent warning messages)
-a [arch] set asm.arch
-A run 'aaa' command to analyze all referenced code
-b [bits] set asm.bits
-B [baddr] set base address for PIE binaries
-c 'cmd..' execute radare command
-C file is host:port (alias for -c+=http://%s/cmd/)
-d debug the executable 'file' or running process 'pid'
-D [backend] enable debug mode (e cfg.debug=true)
-e k=v evaluate config var
-f block size = file size
-F [binplug] force to use that rbin plugin
-h, -hh show help message, -hh for long
-H ([var]) display variable
-i [file] run script file
-I [file] run script file before the file is opened
-k [OS/kern] set asm.os (linux, macos, w32, netbsd, ...)
-l [lib] load plugin file
-L list supported IO plugins

28
Command-line Flags

-m [addr] map file at given address (loadaddr)

-M do not demangle symbol names
-n, -nn do not load RBin info (-nn only load bin structures)
-N do not load user settings and scripts
-q quiet mode (no prompt) and quit after -i
-Q quiet mode (no prompt) and quit faster (quickLeak=true)
-p [prj] use project, list if no arg, load if no file
-P [file] apply rapatch file and quit
-r [rarun2] specify rarun2 profile to load (same as -e dbg.profile=X)
-R [rr2rule] specify custom rarun2 directive
-s [addr] initial seek
-S start r2 in sandbox mode
-t load rabin2 info in thread
-u set bin.filter=false to get raw sym/sec/cls names
-v, -V show radare2 version (-V show lib versions)
-w open file in write mode
-x open without exec-flag (asm.emu will not work), See io.exec
-X same as -e bin.usextr=false (useful for dyldcache)
-z, -zz do not load strings or load them even in raw

Common usage patterns

Open a file in write mode without parsing the file format headers.

$ r2 -nw file

Quickly get into an r2 shell without opening any file.

$ r2 -

Specify which sub-binary you want to select when opening a fatbin file:

$ r2 -a ppc -b 32 ls.fat

Run a script before showing interactive command-line prompt:

$ r2 -i patch.r2 target.bin

Execute a command and quit without entering the interactive mode:

$ r2 -qc ij hi.bin > imports.json

29
Command-line Flags

Set the configuration variable:

$ r2 -e scr.color=0 blah.bin

Debug a program:

$ r2 -d ls

Use an existing project file:

$ r2 -p test

30
Command Format

Command Format
A general format for radare2 commands is as follows:

[.][times][cmd][~grep][@[@iter]addr!size][|>pipe] ;

People who use Vim daily and are familiar with its commands will find themselves at home. You will
see this format used throughout the book. Commands are identified by a single case-sensitive character
[a-zA-Z].

To repeatedly execute a command, prefix the command with a number:

px # run px
3px # run px 3 times

The ! prefix is used to execute a command in shell context. If you want to use the cmd callback from
the I/O plugin you must prefix with =! .

Note that a single exclamation mark will run the command and print the output through the RCons API.
This means that the execution will be blocking and not interactive. Use double exclamation marks --
!! -- to run a standard system call.

All the socket, filesystem and execution APIs can be restricted with the cfg.sandbox configuration
variable.

A few examples:

ds ; call the debugger's 'step' command

px 200 @ esp ; show 200 hex bytes at esp
pc > file.c ; dump buffer as a C byte array to file.c
wx 90 @@ sym.* ; write a nop on every symbol
pd 2000 | grep eax ; grep opcodes that use the 'eax' register
px 20 ; pd 3 ; px 40 ; multiple commands in a single line

The standard UNIX pipe | is also available in the radare2 shell. You can use it to filter the output of
an r2 command with any shell program that reads from stdin, such as grep , less , wc . If you do not
want to spawn anything, or you can't, or the target system does not have the basic UNIX tools you need
(Windows or embedded users), you can also use the built-in grep ( ~ ).

31
Command Format

See ?~? for help.

The ~ character enables internal grep-like function used to filter output of any command:

pd 20~call ; disassemble 20 instructions and grep output for 'call'

Additionally, you can grep either for columns or for rows:

pd 20~call:0 ; get first row

pd 20~call:1 ; get second row
pd 20~call[0] ; get first column
pd 20~call[1] ; get second column

Or even combine them:

pd 20~call:0[0] ; grep the first column of the first row matching 'call'

This internal grep function is a key feature for scripting radare2, because it can be used to iterate over a
list of offsets or data generated by disassembler, ranges, or any other command. Refer to the loops
section (iterators) for more information.

The @ character is used to specify a temporary offset at which the command to its left will be
executed. The original seek position in a file is then restored.

For example, pd 5 @ 0x100000fce to disassemble 5 instructions at address 0x100000fce.

Most of the commands offer autocompletion support using <TAB> key, for example s eek or f lags
commands. It offers autocompletion using all possible values, taking flag names in this case. Note that it
is possible to see the history of the commands using the !~... command - it offers a visual mode to
scroll through the radare2 command history.

To extend the autocompletion support to handle more commands or enable autocompletion to your own
commands defined in core, I/O plugins you must use the !!! command.

32
Expressions

Expressions
Expressions are mathematical representations of 64-bit numerical values. They can be displayed in
different formats, be compared or used with all commands accepting numeric arguments. Expressions
can use traditional arithmetic operations, as well as binary and boolean ones. To evaluate mathematical
expressions prepend them with command ? :

[0xb7f9d810]> ?vi 0x8048000

134512640
[0xv7f9d810]> ?vi 0x8048000+34
134512674
[0xb7f9d810]> ?vi 0x8048000+0x34
134512692
[0xb7f9d810]> ? 1+2+3-4*3
hex 0xfffffffffffffffa
octal 01777777777777777777772
unit 17179869184.0G
segment fffff000:0ffa
int64 -6
string "\xfa\xff\xff\xff\xff\xff\xff\xff"
binary 0b1111111111111111111111111111111111111111111111111111111111111010
fvalue: -6.0
float: nanf
double: nan
trits 0t11112220022122120101211020120210210211201

Supported arithmetic operations are:

+ : addition
- : subtraction
* : multiplication
/ : division
% : modulus
> : shift right
< : shift left

[0x00000000]> ?vi 1+2+3

To use of logical OR should quote the whole command to avoid executing the | pipe:

33
Expressions

[0x00000000]> "? 1 | 2"

hex 0x3
octal 03
unit 3
segment 0000:0003
int32 3
string "\x03"
binary 0b00000011
fvalue: 2.0
float: 0.000000f
double: 0.000000
trits 0t10

Numbers can be displayed in several formats:

0x033 : hexadecimal can be displayed

3334 : decimal
sym.fo : resolve flag offset
10K : KBytes 10*1024
10M : MBytes 10*1024*1024

You can also use variables and seek positions to build complex expressions.

Use the ?$? command to list all the available commands or read the refcard chapter of this book.

$$ here (the current virtual seek)

$l opcode length
$s file size
$j jump address (e.g. jmp 0x10, jz 0x10 => 0x10)
$f jump fail address (e.g. jz 0x10 => next instruction)
$m opcode memory reference (e.g. mov eax,[0x10] => 0x10)
$b block size

Some more examples:

[0x4A13B8C0]> ? $m + $l
140293837812900 0x7f98b45df4a4 03771426427372244 130658.0G 8b45d000:04a4 140293837812900
10100100 140293837812900.0 -0.000000

[0x4A13B8C0]> pd 1 @ +$l
0x4A13B8C2 call 0x4a13c000

34
Expressions

35
Basic Debugger Session

Basic Debugger Session

To debug a program, start radare with the -d option. Note that you can attach to a running process by
specifying its PID, or you can start a new program by specifying its name and parameters:

$ pidof mc
32220
$ r2 -d 32220
$ r2 -d /bin/ls
$ r2 -a arm -b 16 -d gdb://192.168.1.43:9090
...

In the second case, the debugger will fork and load the debugee ls program in memory.

It will pause its execution early in ld.so dynamic linker. As a result, you will not yet see the
entrypoint or any shared libraries at this point.

You can override this behavior by setting another name for an entry breakpoint. To do this, add a radare
command e dbg.bep=entry or e dbg.bep=main to your startup script, usually it is
~/.config/radare2/radare2rc .

Another way to continue until a specific address is by using the dcu command. Which means: "debug
continue until" taking the address of the place to stop at. For example:

dcu main

Be warned that certain malware or other tricky programs can actually execute code before main() and
thus you'll be unable to control them. (Like the program constructor or the tls initializers)

Below is a list of most common commands used with debugger:

36
Basic Debugger Session

> d? ; get help on debugger commands

> ds 3 ; step 3 times
> db 0x8048920 ; setup a breakpoint
> db -0x8048920 ; remove a breakpoint
> dc ; continue process execution
> dcs ; continue until syscall
> dd ; manipulate file descriptors
> dm ; show process maps
> dmp A S rwx ; change permissions of page at A and size S
> dr eax=33 ; set register value. eax = 33

There is another option for debugging in radare, which may be easier: using visual mode.

That way you will neither need to remember many commands nor to keep program state in your mind.

To enter visual debugger mode use Vpp :

[0xb7f0c8c0]> Vpp

The initial view after entering visual mode is a hexdump view of the current target program counter
(e.g., EIP for x86). Pressing p will allow you to cycle through the rest of visual mode views. You can
press p and P to rotate through the most commonly used print modes. Use F7 or s to step into and
F8 or S to step over current instruction. With the c key you can toggle the cursor mode to mark a
byte range selection (for example, to later overwrite them with nop). You can set breakpoints with F2
key.

In visual mode you can enter regular radare commands by prepending them with : . For example, to
dump a one block of memory contents at ESI:

<Press ':'>
x @ esi

To get help on visual mode, press ? . To scroll the help screen, use arrows. To exit the help view, press
q .

A frequently used command is dr , which is used to read or write values of the target's general purpose
registers. For a more compact register value representation you might use dr= command. You can also
manipulate the hardware and the extended/floating point registers.

37
Contributing to radare2

Contributing
Radare2 Book
If you want to contribute to the Radare2 book, you can do it at the Github repository. Suggested
contributions include:

Crackme writeups
CTF writeups
Documentation on how to use Radare2
Documentation on developing for Radare2
Conference presentations/workshops using Radare2
Missing content from the Radare1 book updated to Radare2

Please get permission to port any content you do not own/did not create before you put it in the Radare2
book.

See https://github.com/radare/radare2/blob/master/DEVELOPERS.md for general help on contributing

to radare2.

38
Configuration

Configuration
The core reads ~/.config/radare2/radare2rc while starting. You can add e commands to this file
to tune the radare2 configuration to your taste.

To prevent radare2 from parsing this file at startup, pass it the -N option.

All the configuration of radare2 is done with the eval commands. A typical startup configuration file
looks like this:

$ cat ~/.radare2rc
e scr.color = 1
e dbg.bep = loader

The configuration can also be changed with -e command-line option. This way you can adjust
configuration from the command line, keeping the .radare2rc file intact. For example, to start with
empty configuration and then adjust scr.color and asm.syntax the following line may be used:

$ radare2 -N -e scr.color=1 -e asm.syntax=intel -d /bin/ls

Internally, the configuration is stored in a hash table. The variables are grouped in namespaces: cfg. ,
file. , dbg. , scr. and so on.

To get a list of all configuration variables just type e in the command line prompt. To limit the output
to a selected namespace, pass it with an ending dot to e . For example, e file. will display all
variables defined inside the "file" namespace.

To get help about e command type e? :

39
Configuration

Usage: e[?] [var[=value]]

e? show this help
e?asm.bytes show description
e?? list config vars with description
e list config vars
e- reset config vars
e* dump config vars in r commands
e!a invert the boolean value of 'a' var
er [key] set config key as readonly. no way back
ec [k] [color] set color for given key (prompt, offset, ...)
e a get value of var 'a'
e a=b set var 'a' the 'b' value
env [k[=v]] get/set environment variable

A simpler alternative to the e command is accessible from the visual mode. Type Ve to enter it, use
arrows (up, down, left, right) to navigate the configuration, and q to exit it. The start screen for the
visual configuration edit looks like this:

[EvalSpace]

> anal
asm
scr
asm
bin
cfg
diff
dir
dbg
cmd
fs
hex
http
graph
hud
scr
search
io

For configuration values that can take one of several values, you can use the =? operator to get a list
of valid values:

[0x00000000]> e scr.nkey = ?
scr.nkey = fun, hit, flag

40
Configuration

41
Colors

Colors
Console access is wrapped in API that permits to show the output of any command as ANSI, W32
Console or HTML formats. This allows radare's core to run inside environments with limited displaying
capabilities, like kernels or embedded devices. It is still possible to receive data from it in your favorite
format.

To enable colors support by default, add a corresponding configuration option to the .radare2
configuration file:

$ echo 'e scr.color=1' >> ~/.radare2rc

Note that enabling colors is not a boolean option. Instead, it is a number because there are different
color depth levels. This is:

0: black and white

1: 16 basic ANSI colors
2: 256 scale colors
3: 24bit true color

The reason for having such user-defined options is because there's no standard or portable way for the
terminal programs to query the console to determine the best configuration, same goes for charset
encodings, so r2 allows you to choose that by hand.

Usually, serial consoles may work with 0 or 1, while xterms may support up to 3. RCons will try to find
the closest color scheme for your theme when you choose a different them with the eco command.

It is possible to configure the color of almost any element of disassembly output. For *NIX terminals, r2
accepts color specification in RGB format. To change the console color palette use ec command.

Type ec to get a list of all currently used colors. Type ecs to show a color palette to pick colors
from:

42
Colors

43
Colors

Themes
You can create your own color theme, but radare2 have its own predefined ones. Use the eco

command to list or select them.

In visual mode use the R key to randomize colors or choose the next theme in the list.

44
Configuration Variables

Configuration Variables
Below is a list of the most frequently used configuration variables. You can get a complete list by
issuing e command without arguments. For example, to see all variables defined in the "cfg"
namespace, issue e cfg. (mind the ending dot). You can get help on any eval configuration variable
by using e? cfg.

The e?? command to get help on all the evaluable configuration variables of radare2. As long as the
output of this command is pretty large you can combine it with the internal grep ~ to filter for what
you are looking for:

The Visual mode has an eval browser that is accessible through the Vbe command.

asm.arch
Defines the target CPU architecture used for disassembling ( pd , pD commands) and code analysis
( a command). You can find the list of possible values by looking at the result of e asm.arch=? or
rasm2 -L . It is quite simple to add new architectures for disassembling and analyzing code. There is

an interface for that. For x86, it is used to attach a number of third-party disassembler engines,
including GNU binutils, Udis86 and a few handmade ones.

asm.bits
Determines width in bits of registers for the current architecture. Supported values: 8, 16, 32, 64. Note
that not all target architectures support all combinations for asm.bits.

asm.syntax
Changes syntax flavor for disassembler between Intel and AT&T. At the moment, this setting affects
Udis86 disassembler for Intel 32/Intel 64 targets only. Supported values are intel and att .

asm.pseudo
45
Configuration Variables

A boolean value to choose a string disassembly engine. "False" indicates a native one, defined by the
current architecture, "true" activates a pseudocode strings format; for example, it will show eax=ebx
instead of a mov eax, ebx .

asm.os
Selects a target operating system of currently loaded binary. Usually, OS is automatically detected by
rabin -rI . Yet, asm.os can be used to switch to a different syscall table employed by another OS.

asm.flags
If defined to "true", disassembler view will have flags column.

asm.lines.call
If set to "true", draw lines at the left of the disassemble output ( pd , pD commands) to graphically
represent control flow changes (jumps and calls) that are targeted inside current block. Also, see
asm.linesout .

asm.linesout
When defined as "true", the disassembly view will also draw control flow lines that go outside of the
block.

asm.linestyle
A boolean value which changes the direction of control flow analysis. If set to "false", it is done from
top to bottom of a block; otherwise, it goes from bottom to top. The "false" setting seems to be a better
choice for improved readability and is the default one.

asm.offset
Boolean value which controls the visibility of offsets for individual disassembled instructions.

asm.trace
A boolean value that controls displaying of tracing information (sequence number and counter) at the
left of each opcode. It is used to assist with programs trace analysis.

46
Configuration Variables

asm.bytes
A boolean value used to show or hide displaying of raw bytes of instructions.

cfg.bigendian
Change endianness. "true" means big-endian, "false" is for little-endian. "file.id" and "file.flag" both to
be true.

cfg.newtab
If this variable is enabled, help messages will be displayed along with command names in tab
completion for commands.

scr.color
This variable specifies the mode for colorized screen output: "false" (or 0) means no colors, "true" (or 1)
means 16-colors mode, 2 means 256-colors mode, 3 means 16 million-colors mode. If your favorite
theme looks weird, try to bump this up.

scr.seek
This variable accepts a full-featured expression or a pointer/flag (eg. eip). If set, radare will set seek
position to its value on startup.

cfg.fortunes
Enables or disables "fortune" messages displayed at each radare start.

cfg.fortunes.type
Fortunes are classified by type. This variable determines which types are allowed for displaying when
cfg.fortunes is true , so they can be fine-tuned on what's appropriate for the intended audience.

Current types are tips , fun , nsfw , creepy .

47
Files

Files
Use r2 -H to list all the environment variables that matter to know where it will be looking for files.
Those paths depend on the way (and operating system) you have built r2 for.

R2_PREFIX=/usr
MAGICPATH=/usr/share/radare2/2.8.0-git/magic
PREFIX=/usr
INCDIR=/usr/include/libr
LIBDIR=/usr/lib64
LIBEXT=so
RCONFIGHOME=/home/user/.config/radare2
RDATAHOME=/home/user/.local/share/radare2
RCACHEHOME=/home/user/.cache/radare2
LIBR_PLUGINS=/usr/lib/radare2/2.8.0-git
USER_PLUGINS=/home/user/.local/share/radare2/plugins
USER_ZIGNS=/home/user/.local/share/radare2/zigns

RC Files
RC files are r2 scripts that are loaded at startup time. Those files must be in 3 different places:

System
radare2 will first try to load /usr/share/radare2/radare2rc

Your Home
Each user in the system can have its own r2 scripts to run on startup to select the color scheme, and
other custom options by having r2 commands in there.

~/.radare2rc
~/.config/radare2/radare2rc
~/.config/radare2/radare2rc.d/

Target file

48
Files

If you want to run a script everytime you open a file, just create a file with the same name of the file but
appending .r2 to it.

49
Basic Commands

Basic Commands
Most command names in radare are derived from action names. They should be easy to remember, as
they are short. Actually, all commands are single letters. Subcommands or related commands are
specified using the second character of the command name. For example, / foo is a command to
search plain string, while /x 90 90 is used to look for hexadecimal pairs.

The general format for a valid command (as explained in the Command Format chapter) looks like this:

[.][times][cmd][~grep][@[@iter]addr!size][|>pipe] ; ...

For example,

> 3s +1024 ; seeks three times 1024 from the current seek

If a command starts with =! , the rest of the string is passed to the currently loaded IO plugin (a
debugger, for example). Most plugins provide help messages with =!? or =!help .

$ r2 -d /bin/ls
> =!help ; handled by the IO plugin

If a command starts with ! , posix_system() is called to pass the command to your shell. Check !?
for more options and usage examples.

> !ls ; run `ls` in the shell

The meaning of the arguments (iter, addr, size) depends on the specific command. As a rule of thumb,
most commands take a number as an argument to specify the number of bytes to work with, instead of
the currently defined block size. Some commands accept math expressions or strings.

> px 0x17 ; show 0x17 bytes in hexs at current seek

> s base+0x33 ; seeks to flag 'base' plus 0x33
> / lib ; search for 'lib' string.

50
Basic Commands

The @ sign is used to specify a temporary offset location or a seek position at which the command is
executed, instead of current seek position. This is quite useful as you don't have to seek around all the
time.

> p8 10 @ 0x4010 ; show 10 bytes at offset 0x4010

> f patata @ 0x10 ; set 'patata' flag at offset 0x10

Using @@ you can execute a single command on a list of flags matching the glob. You can think of this
as a foreach operation:

> s 0
> / lib ; search 'lib' string
> p8 20 @@ hit0_* ; show 20 hexpairs at each search hit

The > operation is used to redirect the output of a command into a file (overwriting it if it already
exists).

> pr > dump.bin ; dump 'raw' bytes of current block to file named 'dump.bin'
> f > flags.txt ; dump flag list to 'flags.txt'

The | operation (pipe) is similar to what you are used to expect from it in a *NIX shell: an output of
one command as input to another.

[0x4A13B8C0]> f | grep section | grep text

0x0805f3b0 512 section._text
0x080d24b0 512 section._text_end

You can pass several commands in a single line by separating them with a semicolon ; :

> px ; dr

51
Seeking

Seeking
To move around the file we are inspecting we will need to change the offset at which we are using the
s command.

The argument is a math expression that can contain flag names, parenthesis, addition, substraction,
multiplication of immediates of contents of memory using brackets.

Some example commands:

[0x00000000]> s 0x10
[0x00000010]> s+4
[0x00000014]> s-
[0x00000010]> s+
[0x00000014]>

Observe how the prompt offset changes. The first line moves the current offset to the address 0x10.

The second does a relative seek 4 bytes forward.

And finally, the last 2 commands are undoing, and redoing the last seek operations.

Instead of using just numbers, we can use complex expressions, or basic arithmetic operations to
represent the address to seek.

To do this, check the ?$? Help message which describes the internal variables that can be used in the
expressions. For example, this is the same as doing s+4 .

[0x00000000]> s $$+4

From the debugger (or when emulating) we can also use the register names as references. They are
loaded as flags with the .dr* command, which happens under the hood.

[0x00000000]> s rsp+0x40

Here's the full help of the s command. We will explain in more detail below.

52
Seeking

[0x00000000]> s?
Usage: s[+-] [addr]
s print current address
s 0x320 seek to this address
s- undo seek
s+ redo seek
s* list undo seek history
s++ seek blocksize bytes forward
s-- seek blocksize bytes backward
s+ 512 seek 512 bytes forward
s- 512 seek 512 bytes backward
sg/sG seek begin (sg) or end (sG) of section or file
s.hexoff Seek honoring a base from core->offset
sa [[+-]a] [asz] seek asz (or bsize) aligned to addr
sn/sp seek next/prev scr.nkey
s/ DATA search for next occurrence of 'DATA'
s/x 9091 search for next occurrence of \x90\x91
sb seek aligned to bb start
so [num] seek to N next opcode(s)
sf seek to next function (f->addr+f->size)
sC str seek to comment matching given string
sr pc seek to register

> 3s++ ; 3 times block-seeking

> s 10+0x80 ; seek at 0x80+10

If you want to inspect the result of a math expression, you can evaluate it using the ? command.
Simply pass the expression as an argument. The result can be displayed in hexadecimal, decimal, octal
or binary formats.

> ? 0x100+200
0x1C8 ; 456d ; 710o ; 1100 1000

There are also subcommands of ? that display the output in one specific format (base 10, base 16 ,...).
See ?v and ?vi .

In the visual mode, you can press u (undo) or U (redo) inside the seek history to return back to
previous or forward to the next location.

Open file
As a test file, let's use a simple hello_world.c compiled in Linux ELF format. After we compile it
let's open it with radare2:

53
Seeking

$ r2 hello_world

Now we have the command prompt:

[0x00400410]>

And it is time to go deeper.

Seeking at any position

All seeking commands that take an address as a command parameter can use any numeral base such as
hex, octal, binary or decimal.

Seek to an address 0x0. An alternative command is simply 0x0

[0x00400410]> s 0x0
[0x00000000]>

Print current address:

[0x00000000]> s
0x0
[0x00000000]>

There is an alternate way to print current position: ?v $$ .

Seek N positions forward, space is optional:

[0x00000000]> s+ 128
[0x00000080]>

Undo last two seeks to return to the initial address:

[0x00000080]> s-
[0x00000000]> s-
[0x00400410]>

We are back at 0x00400410.

54
Seeking

There's also a command to show the seek history:

[0x00400410]> s*
f undo_3 @ 0x400410
f undo_2 @ 0x40041a
f undo_1 @ 0x400410
f undo_0 @ 0x400411
# Current undo/redo position.
f redo_0 @ 0x4005b4

55
Block Size

Block Size
The block size determines how many bytes radare2 commands will process when not given an explicit
size argument. You can temporarily change the block size by specifying a numeric argument to the print
commands. For example px 20 .

The b command is used to change the block size:

[0x00000000]> b 0x100 ; block size = 0x100

[0x00000000]> b +16 ; ... = 0x110
[0x00000000]> b -32 ; ... = 0xf0

The bf command is used to change the block size to value specified by a flag. For example, in
symbols, the block size of the flag represents the size of the function.

[0x00000000]> bf sym.main ; block size = sizeof(sym.main)

[0x00000000]> pd @ sym.main ; disassemble sym.main
...

You can combine two operations in a single one ( pdf ):

[0x00000000]> pdf @ sym.main

56
Sections

Sections
The concept of sections is tied to the information extracted from the binary. We can display this
information by using the i command.

Displaying information about sections:

[0x00005310]> iS
[Sections]
00 0x00000000 0 0x00000000 0 ----
01 0x00000238 28 0x00000238 28 -r-- .interp
02 0x00000254 32 0x00000254 32 -r-- .note.ABI_tag
03 0x00000278 176 0x00000278 176 -r-- .gnu.hash
04 0x00000328 3000 0x00000328 3000 -r-- .dynsym
05 0x00000ee0 1412 0x00000ee0 1412 -r-- .dynstr
06 0x00001464 250 0x00001464 250 -r-- .gnu.version
07 0x00001560 112 0x00001560 112 -r-- .gnu.version_r
08 0x000015d0 4944 0x000015d0 4944 -r-- .rela.dyn
09 0x00002920 2448 0x00002920 2448 -r-- .rela.plt
10 0x000032b0 23 0x000032b0 23 -r-x .init
...

As you may know, binaries have sections and maps. The sections define the contents of a portion of the
file that can be mapped in memory (or not). What is mapped is defined by the segments.

Before the IO refactoring done by condret, the S command was used to manage what we now call
maps. Currently the S command is deprecated because iS and om should be enough.

Firmware images, bootloaders and binary files usually place various sections of a binary at different
addresses in memory. To represent this behavior, radare offers the iS . Use iS? to get the help
message. To list all created sections use iS (or iSj to get the json format). The iS= will show the
region bars in ascii-art.

You can create a new mapping using the om subcommand as follows:

om fd vaddr [size] [paddr] [rwx] [name]

For Example:

[0x0040100]> om 4 0x00000100 0x00400000 0x0001ae08 rwx test

57
Sections

You can also use om command to view information about mapped sections:

[0x00401000]> om
6 fd: 4 +0x0001ae08 0x00000100 - 0x004000ff rwx test
5 fd: 3 +0x00000000 0x00000000 - 0x0000055f r-- fmap.LOAD0
4 fd: 3 +0x00001000 0x00001000 - 0x000011e4 r-x fmap.LOAD1
3 fd: 3 +0x00002000 0x00002000 - 0x0000211f r-- fmap.LOAD2
2 fd: 3 +0x00002de8 0x00003de8 - 0x0000402f r-- fmap.LOAD3
1 fd: 4 +0x00000000 0x00004030 - 0x00004037 rw- mmap.LOAD3

Use om? to get all the possible subcommands. To list all the defined maps use om (or omj to get the
json format or om* to get the r2 commands format). To get the ascii art view use om= .

It is also possible to delete the mapped section using the om-mapid command.

For Example:

[0x00401000]> om-6

58
Mapping Files

Mapping Files
Radare's I/O subsystem allows you to map the contents of files into the same I/O space used to contain a
loaded binary. New contents can be placed at random offsets.

The o command permits the user to open a file, this is mapped at offset 0 unless it has a known binary
header and then the maps are created in virtual addresses.

Sometimes, we want to rebase a binary, or maybe we want to load or map the file in a different address.

When launching r2, the base address can be changed with the -B flag. But you must notice the
difference when opening files with unknown headers, like bootloaders, so we need to map them using
the -m flag (or specifying it as argument to the o command).

radare2 is able to open files and map portions of them at random places in memory specifying attributes
like permissions and name. It is the perfect basic tooling to reproduce an environment like a core file, a
debug session, by also loading and mapping all the libraries the binary depends on.

Opening files (and mapping them) is done using the o (open) command. Let's read the help:

59
Mapping Files

Prepare a simple layout:

$ rabin2 -l /bin/ls
[Linked libraries]
libselinux.so.1
librt.so.1
libacl.so.1
libc.so.6

4 libraries

Map a file:

[0x00001190]> o /bin/zsh 0x499999

List mapped files:

60
Mapping Files

[0x00000000]> o
- 6 /bin/ls @ 0x0 ; r
- 10 /lib/ld-linux.so.2 @ 0x100000000 ; r
- 14 /bin/zsh @ 0x499999 ; r

Print hexadecimal values from /bin/zsh:

[0x00000000]> px @ 0x499999

Unmap files using the o- command. Pass the required file descriptor to it as an argument:

[0x00000000]> o-14

61
Print Modes

Print Modes
One of the key features of radare2 is displaying information in many formats. The goal is to offer a
selection of display choices to interpret in the best possible way binary data.

Binary data can be represented as integers, shorts, longs, floats, timestamps, hexpair strings, or more
complex formats like C structures, disassembly listings, decompilation listing, be a result of an external
processing...

Below is a list of available print modes listed by p? :

| pd[?] [sz] [a] [b] disassemble N opcodes (pd) or N bytes (pD)

| pf[?][.nam] [fmt] print formatted data (pf.name, pf.name $<expr>)
| ph[?][=|hash] ([len]) calculate hash for a block
| pj[?] [len] print as indented JSON
| p[iI][df] [len] print N ops/bytes (f=func) (see pi? and pdi)
| p[kK] [len] print key in randomart (K is for mosaic)
| pm[?] [magic] print libmagic data (see pm? and /m?)
| pq[?][iz] [len] print QR code with the first Nbytes of the current block
| pr[?][glx] [len] print N raw bytes (in lines or hexblocks, 'g'unzip)
| ps[?][pwz] [len] print pascal/wide/zero-terminated strings
| pt[?][dn] [len] print different timestamps
| pu[?][w] [len] print N url encoded bytes (w=wide)
| pv[?][jh] [mode] show variable/pointer/value in memory
| pwd display current working directory
| px[?][owq] [len] hexdump of N bytes (o=octal, w=32bit, q=64bit)
| pz[?] [len] print zoom view (see pz? for help)
[0x00005310]>

62
Print Modes

Tip: when using json output, you can append the ~{} to the command to get a pretty-printed version
of the output:

[0x00000000]> oj
[{"raised":false,"fd":563280,"uri":"malloc://512","from":0,"writable":true,"size":512,"o
verlaps":false}]
[0x00000000]> oj~{}
[
{
"raised": false,
"fd": 563280,
"uri": "malloc://512",
"from": 0,
"writable": true,
"size": 512,
"overlaps": false
}
]

For more on the magical powers of ~ see the help in ?@? , and the Command Format chapter earlier
in the book.

Hexadecimal View
px gives a user-friendly output showing 16 pairs of numbers per row with offsets and raw
representations:

Show Hexadecimal Words Dump (32 bits)

63
Print Modes

8 bits Hexpair List of Bytes

[0x00404888]> p8 16
31ed4989d15e4889e24883e4f0505449

Show Hexadecimal Quad-words Dump (64 bits)

Date/Time Formats
Currently supported timestamp output modes are:

For example, you can 'view' the current buffer as timestamps in the ntfs time:

[0x08048000]> e cfg.bigendian = false

[0x08048000]> pt 4
29:04:32948 23:12:36 +0000
[0x08048000]> e cfg.bigendian = true
[0x08048000]> pt 4
20:05:13001 09:29:21 +0000

As you can see, the endianness affects the result. Once you have printed a timestamp, you can grep the
output, for example, by year:

[0x08048000]> pt ~1974 | wc -l
15
[0x08048000]> pt ~2022
27:04:2022 16:15:43 +0000

64
Print Modes

The default date format can be configured using the cfg.datefmt variable. Formatting rules for it
follow the well known strftime(3) format. Check the manpage for more details, but these are the most
important:

%a The abbreviated name of the day of the week according to the current locale.
%A The full name of the day of the week according to the current locale.
%d The day of the month as a decimal number (range 01 to 31).
%D Equivalent to %m/%d/%y. (Yecch—for Americans only).
%H The hour as a decimal number using a 24-hour clock (range 00 to 23).
%I The hour as a decimal number using a 12-hour clock (range 01 to 12).
%m The month as a decimal number (range 01 to 12).
%M The minute as a decimal number (range 00 to 59).
%p Either "AM" or "PM" according to the given time value.
%s The number of seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC). (TZ)
%S The second as a decimal number (range 00 to 60). (The range is up to 60 to allow fo
r occasional leap seconds.)
%T The time in 24-hour notation (%H:%M:%S). (SU)
%y The year as a decimal number without a century (range 00 to 99).
%Y The year as a decimal number including the century.
%z The +hhmm or -hhmm numeric timezone (that is, the hour and minute offset from UTC).
(SU)
%Z The timezone name or abbreviation.

Basic Types
There are print modes available for all basic types. If you are interested in a more complex structure,
type pf?? for format characters and pf??? for examples:

65
Print Modes

Use triple-question-mark pf??? to get some examples using print format strings.

66
Print Modes

[0x00499999]> pf???
|pf: pf[.k[.f[=v]]|[v]]|[n]|[0|cnt][fmt] [a0 a1 ...]
| Examples:
| pf 3xi foo bar 3-array of struct, each with named fields
: 'foo' as hex, and 'bar' as int
| pf B (BitFldType)arg_name` bitfield type
| pf E (EnumType)arg_name` enum type
| pf.obj xxdz prev next size name Define the obj format as xxdz
| pf obj=xxdz prev next size name Same as above
| pf iwq foo bar troll Print the iwq format with foo, bar, troll
as the respective names for the fields
| pf 0iwq foo bar troll Same as above, but considered as a union
(all fields at offset 0)
| pf.plop ? (troll)mystruct Use structure troll previously defined
| pf 10xiz pointer length string Print a size 10 array of the xiz struct w
ith its field names
| pf {integer}? (bifc) Print integer times the following format
(bifc)
| pf [4]w[7]i Print an array of 4 words and then an arr
ay of 7 integers
| pf ic...?i foo bar "(pf xw yo foo)troll" yo Print nested anonymous structres
| pfn2 print signed short (2 bytes) value. Use N
insted of n for printing unsigned values

Some examples are below:

[0x4A13B8C0]> pf i
0x00404888 = 837634441

[0x4A13B8C0]> pf
0x00404888 = 837634432.000000

High-level Languages Views

Valid print code formats for human-readable languages are:

pc C

pc* print 'wx' r2 commands

pch C half-words (2 byte)

pcw C words (4 byte)

pcd C dwords (8 byte)

pca GAS .byte blob

pcA .bytes with instructions in comments

67
Print Modes

pcs string

pcS shellscript that reconstructs the bin

pcj json

pcJ javascript

pcp python

If we need to create a .c file containing a binary blob, use the pc command, that creates this output.
The default size is like in many other commands: the block size, which can be changed with the b
command.

But we can just temporarily override this block size by expressing it as an argument.

[0xB7F8E810]> pc 32
#define _BUFFER_SIZE 32
unsigned char buffer[_BUFFER_SIZE] = {
0x89, 0xe0, 0xe8, 0x49, 0x02, 0x00, 0x00, 0x89, 0xc7, 0xe8, 0xe2, 0xff, 0xff, 0xff, 0x81
, 0xc3, 0xd6, 0xa7, 0x01, 0x00, 0x8b, 0x83, 0x00, 0xff, 0xff, 0xff, 0x5a, 0x8d, 0x24, 0x
84, 0x29, 0xc2 };

That cstring can be used in many programming languages, not just C.

[0x7fcd6a891630]> pcs
"\x48\x89\xe7\xe8\x68\x39\x00\x00\x49\x89\xc4\x8b\x05\xef\x16\x22\x00\x5a\x48\x8d\x24\xc
4\x29\xc2\x52\x48\x89\xd6\x49\x89\xe5\x48\x83\xe4\xf0\x48\x8b\x3d\x06\x1a

Strings
Strings are probably one of the most important entry points when starting to reverse engineer a program
because they usually reference information about functions' actions (asserts, debug or info messages...).
Therefore, radare supports various string formats:

68
Print Modes

Most strings are zero-terminated. Below there is an example using the debugger to continue the
execution of a program until it executes the 'open' syscall. When we recover the control over the
process, we get the arguments passed to the syscall, pointed by %ebx. In the case of the 'open' call, it is
a zero terminated string which we can inspect using psz .

[0x4A13B8C0]> dcs open

0x4a14fc24 syscall(5) open ( 0x4a151c91 0x00000000 0x00000000 ) = 0xffffffda
[0x4A13B8C0]> dr
eax 0xffffffda esi 0xffffffff eip 0x4a14fc24
ebx 0x4a151c91 edi 0x4a151be1 oeax 0x00000005
ecx 0x00000000 esp 0xbfbedb1c eflags 0x200246
edx 0x00000000 ebp 0xbfbedbb0 cPaZstIdor0 (PZI)
[0x4A13B8C0]>
[0x4A13B8C0]> psz @ 0x4a151c91
/etc/ld.so.cache

Print Memory Contents

It is also possible to print various packed data types using the pf command:

[0xB7F08810]> pf xxS @ rsp

0x7fff0d29da30 = 0x00000001
0x7fff0d29da34 = 0x00000000
0x7fff0d29da38 = 0x7fff0d29da38 -> 0x0d29f7ee /bin/ls

This can be used to look at the arguments passed to a function. To achieve this, simply pass a 'format
memory string' as an argument to pf , and temporally change the current seek position/offset using
@ . It is also possible to define arrays of structures with pf . To do this, prefix the format string with a

69
Print Modes

numeric value. You can also define a name for each field of the structure by appending them as a space-
separated arguments list.

[0x4A13B8C0]> pf 2*xw pointer type @ esp

0x00404888 [0] {
pointer :
(*0xffffffff8949ed31) type : 0x00404888 = 0x8949ed31
0x00404890 = 0x48e2
}
0x00404892 [1] {
(*0x50f0e483) pointer : 0x00404892 = 0x50f0e483
type : 0x0040489a = 0x2440
}

A practical example for using pf on a binary of a GStreamer plugin:

$ radare ~/.gstreamer-0.10/plugins/libgstflumms.so
[0x000028A0]> seek sym.gst_plugin_desc
[0x000185E0]> pf iissxsssss major minor name desc _init version \
license source package origin
major : 0x000185e0 = 0
minor : 0x000185e4 = 10
name : 0x000185e8 = 0x000185e8 flumms
desc : 0x000185ec = 0x000185ec Fluendo MMS source
_init : 0x000185f0 = 0x00002940
version : 0x000185f4 = 0x000185f4 0.10.15.1
license : 0x000185f8 = 0x000185f8 unknown
source : 0x000185fc = 0x000185fc gst-fluendo-mms
package : 0x00018600 = 0x00018600 Fluendo MMS source
origin : 0x00018604 = 0x00018604 http://www.fluendo.com

Disassembly
The pd command is used to disassemble code. It accepts a numeric value to specify how many
instructions should be disassembled. The pD command is similar but instead of a number of
instructions, it decompiles a given number of bytes.

d : disassembly N opcodes count of opcodes

D : asm.arch disassembler bsize bytes

[0x00404888]> pd 1
;-- entry0:
0x00404888 31ed xor ebp, ebp

70
Print Modes

Selecting Target Architecture

The architecture flavor for the disassembler is defined by the asm.arch eval variable. You can use e
asm.arch=?? to list all available architectures.

[0x00005310]> e asm.arch=??
_dAe _8_16 6502 LGPL3 6502/NES/C64/Tamagotchi/T-1000 CPU
_dAe _8 8051 PD 8051 Intel CPU
_dA_ _16_32 arc GPL3 Argonaut RISC Core
a___ _16_32_64 arm.as LGPL3 as ARM Assembler (use ARM_AS environment)
adAe _16_32_64 arm BSD Capstone ARM disassembler
_dA_ _16_32_64 arm.gnu GPL3 Acorn RISC Machine CPU
_d__ _16_32 arm.winedbg LGPL2 WineDBG's ARM disassembler
adAe _8_16 avr GPL AVR Atmel
adAe _16_32_64 bf LGPL3 Brainfuck
_dA_ _32 chip8 LGPL3 Chip8 disassembler
_dA_ _16 cr16 LGPL3 cr16 disassembly plugin
_dA_ _32 cris GPL3 Axis Communications 32-bit embedded processor
adA_ _32_64 dalvik LGPL3 AndroidVM Dalvik
ad__ _16 dcpu16 PD Mojang's DCPU-16
_dA_ _32_64 ebc LGPL3 EFI Bytecode
adAe _16 gb LGPL3 GameBoy(TM) (z80-like)
_dAe _16 h8300 LGPL3 H8/300 disassembly plugin
_dAe _32 hexagon LGPL3 Qualcomm Hexagon (QDSP6) V6
_d__ _32 hppa GPL3 HP PA-RISC
_dAe _0 i4004 LGPL3 Intel 4004 microprocessor
_dA_ _8 i8080 BSD Intel 8080 CPU
adA_ _32 java Apache Java bytecode
_d__ _32 lanai GPL3 LANAI
...

Configuring the Disassembler

There are multiple options which can be used to configure the output of the disassembler. All these
options are described in e? asm.

71
Print Modes

[0x00005310]> e? asm.
asm.anal: Analyze code and refs while disassembling (see anal.strings)
asm.arch: Set the arch to be used by asm
asm.assembler: Set the plugin name to use when assembling
asm.bbline: Show empty line after every basic block
asm.bits: Word size in bits at assembler
asm.bytes: Display the bytes of each instruction
asm.bytespace: Separate hexadecimal bytes with a whitespace
asm.calls: Show callee function related info as comments in disasm
asm.capitalize: Use camelcase at disassembly
asm.cmt.col: Column to align comments
asm.cmt.flgrefs: Show comment flags associated to branch reference
asm.cmt.fold: Fold comments, toggle with Vz
...

Currently there are 136 asm. configuration variables so we do not list them all.

Disassembly Syntax
The asm.syntax variable is used to change the flavor of the assembly syntax used by a disassembler
engine. To switch between Intel and AT&T representations:

e asm.syntax = intel
e asm.syntax = att

You can also check asm.pseudo , which is an experimental pseudocode view, and asm.esil which
outputs ESIL ('Evaluable Strings Intermediate Language'). ESIL's goal is to have a human-readable
representation of every opcode semantics. Such representations can be evaluated (interpreted) to
emulate effects of individual instructions.

72
Flags

Flags
Flags are conceptually similar to bookmarks. They associate a name with a given offset in a file. Flags
can be grouped into 'flag spaces'. A flag space is a namespace for flags, grouping together flags of
similar characteristics or type. Examples for flag spaces: sections, registers, symbols.

To create a flag:

[0x4A13B8C0]> f flag_name @ offset

You can remove a flag by appending the - character to command. Most commands accept - as
argument-prefix as an indication to delete something.

[0x4A13B8C0]> f-flag_name

To switch between or create new flagspaces use the fs command:

73
Flags

Here there are some command examples:

[0x4A13B8C0]> fs symbols ; select only flags in symbols flagspace

[0x4A13B8C0]> f ; list only flags in symbols flagspace
[0x4A13B8C0]> fs * ; select all flagspaces
[0x4A13B8C0]> f myflag ; create a new flag called 'myflag'
[0x4A13B8C0]> f-myflag ; delete the flag called 'myflag'

You can rename flags with fr .

Local flags
Every flag name should be unique for addressing reasons. But it is quite a common need to have the
flags, for example inside the functions, with simple and ubiquitous names like loop or return . For
this purpose you can use so called "local" flags, which are tied to the function where they reside. It is
possible to add them using f. command:

74
Flags

[0x00003a04]> pd 10
│ 0x00003a04 48c705c9cc21. mov qword [0x002206d8], 0xffffffffffffffff ;
[0x2206d8:8]=0
│ 0x00003a0f c60522cc2100. mov byte [0x00220638], 0 ; [0x220638:1]=0
│ 0x00003a16 83f802 cmp eax, 2
│ .─< 0x00003a19 0f84880d0000 je 0x47a7
│ │ 0x00003a1f 83f803 cmp eax, 3
│ .──< 0x00003a22 740e je 0x3a32
│ ││ 0x00003a24 83e801 sub eax, 1
│.───< 0x00003a27 0f84ed080000 je 0x431a
││││ 0x00003a2d e8fef8ffff call sym.imp.abort ; void abort(void)
││││ ; CODE XREF from main (0x3a22)
││╰──> 0x00003a32 be07000000 mov esi, 7
[0x00003a04]> f. localflag @ 0x3a32
[0x00003a04]> f.
0x00003a32 localflag [main + 210]
[0x00003a04]> pd 10
│ 0x00003a04 48c705c9cc21. mov qword [0x002206d8], 0xffffffffffffffff ;
[0x2206d8:8]=0
│ 0x00003a0f c60522cc2100. mov byte [0x00220638], 0 ; [0x220638:1]=0
│ 0x00003a16 83f802 cmp eax, 2
│ .─< 0x00003a19 0f84880d0000 je 0x47a7
│ │ 0x00003a1f 83f803 cmp eax, 3
│ .──< 0x00003a22 740e je 0x3a32 ; main.localflag
│ ││ 0x00003a24 83e801 sub eax, 1
│.───< 0x00003a27 0f84ed080000 je 0x431a
││││ 0x00003a2d e8fef8ffff call sym.imp.abort ; void abort(void)
││││ ; CODE XREF from main (0x3a22)
││`──> .localflag:
││││ ; CODE XREF from main (0x3a22)
││`──> 0x00003a32 be07000000 mov esi, 7
[0x00003a04]>

75
Write

Writing Data
Radare can manipulate a loaded binary file in many ways. You can resize the file, move and copy/paste
bytes, insert new bytes (shifting data to the end of the block or file), or simply overwrite bytes. New
data may be given as a wide-string, assembler instructions, or the data may be read in from another file.

Resize the file using the r command. It accepts a numeric argument. A positive value sets a new size
for the file. A negative one will truncate the file to the current seek position minus N bytes.

r 1024 ; resize the file to 1024 bytes

r -10 @ 33 ; strip 10 bytes at offset 33

Write bytes using the w command. It accepts multiple input formats like inline assembly, endian-
friendly dwords, files, hexpair files, wide strings:

76
Write

[0x00404888]> w?
|Usage: w[x] [str] [<file] [<<EOF] [@addr]
| w[1248][+-][n] increment/decrement byte,word..
| w foobar write string 'foobar'
| w0 [len] write 'len' bytes with value 0x00
| w6[de] base64/hex write base64 [d]ecoded or [e]ncoded string
| wa[?] push ebp write opcode, separated by ';'
| waf file assemble file and write bytes
| wao[?] op modify opcode (conditional jump. nop, etc)
| wA[?] r 0 alter/modify opcode at current seek (wA?)
| wb 010203 fill current block with cyclic hexpairs
| wB[-]0xVALUE set or unset bits with given value
| wc list all write changes
| wc[?][ir*?] write cache undo/commit/reset/list (io.cache)
| wd [off] [n] duplicate N bytes from offset to here
| we[?] [nNsxX] [arg] extend write operations (insert vs replace)
| wf -|file write contents of file at current offset
| wh r2 whereis/which shell command
| wm f0ff set cyclick binary write mask hexpair
| wo[?] hex write in block with operation. 'wo?' fmi
| wp[?] -|file apply radare patch file. See wp? fmi
| wr 10 write 10 random bytes
| ws pstring write 1 byte for length and then the string
| wt[f][?] file [sz] write to file (from current seek, blocksize)
| wts host:port [sz] send data to remote host:port via tcp://
| ww foobar write wide string
| wx[?][fs] 9090 write two intel nops (from wxfile or wxseek)
| wv[?] eip+34 write 32-64 bit value
| wz string write zero terminated string (like w + \x00)

Some examples:

[0x00000000]> wx 123456 @ 0x8048300

[0x00000000]> wv 0x8048123 @ 0x8049100
[0x00000000]> wa jmp 0x8048320

Write Over
The wo command (write over) has many subcommands, each combines the existing data with the new
data using an operator. The command is applied to the current block. Supported operators include XOR,
ADD, SUB...

77
Write

It is possible to implement cipher-algorithms using radare core primitives and wo . A sample session
performing xor(90) + add(01, 02):

[0x7fcd6a891630]> px
- offset - 0 1 2 3 4 5 6 7 8 9 A B C D E F
0x7fcd6a891630 4889 e7e8 6839 0000 4989 c48b 05ef 1622
0x7fcd6a891640 005a 488d 24c4 29c2 5248 89d6 4989 e548
0x7fcd6a891650 83e4 f048 8b3d 061a 2200 498d 4cd5 1049
0x7fcd6a891660 8d55 0831 ede8 06e2 0000 488d 15cf e600
[0x7fcd6a891630]> wox 90
[0x7fcd6a891630]> px
- offset - 0 1 2 3 4 5 6 7 8 9 A B C D E F
0x7fcd6a891630 d819 7778 d919 541b 90ca d81d c2d8 1946
0x7fcd6a891640 1374 60d8 b290 d91d 1dc5 98a1 9090 d81d
0x7fcd6a891650 90dc 197c 9f8f 1490 d81d 95d9 9f8f 1490
0x7fcd6a891660 13d7 9491 9f8f 1490 13ff 9491 9f8f 1490
[0x7fcd6a891630]> woa 01 02
[0x7fcd6a891630]> px
- offset - 0 1 2 3 4 5 6 7 8 9 A B C D E F
0x7fcd6a891630 d91b 787a 91cc d91f 1476 61da 1ec7 99a3
0x7fcd6a891640 91de 1a7e d91f 96db 14d9 9593 1401 9593
0x7fcd6a891650 c4da 1a6d e89a d959 9192 9159 1cb1 d959
0x7fcd6a891660 9192 79cb 81da 1652 81da 1456 a252 7c77

78
Write

79
Zoom

Zoom
The zoom is a print mode that allows you to get a global view of the whole file or a memory map on a
single screen. In this mode, each byte represents file_size/block_size bytes of the file. Use the pz
command, or just use Z in the visual mode to toggle the zoom mode.

The cursor can be used to scroll faster through the zoom out view. Pressing z again will zoom-in at
the cursor position.

Let's see some examples:

[0x08049790]> e zoom.byte=h
[0x08049790]> pz // or default pzh
0x00000000 7f00 0000 e200 0000 146e 6f74 0300 0000
0x00000010 0000 0000 0068 2102 00ff 2024 e8f0 007a
0x00000020 8c00 18c2 ffff 0080 4421 41c4 1500 5dff
0x00000030 ff10 0018 0fc8 031a 000c 8484 e970 8648
0x00000040 d68b 3148 348b 03a0 8b0f c200 5d25 7074
0x00000050 7500 00e1 ffe8 58fe 4dc4 00e0 dbc8 b885

[0x08049790]> e zoom.byte=p
[0x08049790]> pz // or pzp
0x00000000 2f47 0609 070a 0917 1e9e a4bd 2a1b 2c27
0x00000010 322d 5671 8788 8182 5679 7568 82a2 7d89
0x00000020 8173 7f7b 727a 9588 a07b 5c7d 8daf 836d
0x00000030 b167 6192 a67d 8aa2 6246 856e 8c9b 999f
0x00000040 a774 96c3 b1a4 6c8e a07c 6a8f 8983 6a62
0x00000050 7d66 625f 7ea4 7ea6 b4b6 8b57 a19f 71a2

80
Zoom

[0x08049790]> eval zoom.byte = flags

[0x08049790]> pz // or pzf
0x00406e65 48d0 80f9 360f 8745 ffff ffeb ae66 0f1f
0x00406e75 4400 0083 f801 0f85 3fff ffff 410f b600
0x00406e85 3c78 0f87 6301 0000 0fb6 c8ff 24cd 0026
0x00406e95 4100 660f 1f84 0000 0000 0084 c074 043c
0x00406ea5 3a75 18b8 0500 0000 83f8 060f 95c0 e9cd
0x00406eb5 feff ff0f 1f84 0000 0000 0041 8801 4983
0x00406ec5 c001 4983 c201 4983 c101 e9ec feff ff0f

[0x08049790]> e zoom.byte=F
[0x08049790]> pO // or pzF
0x00000000 0000 0000 0000 0000 0000 0000 0000 0000
0x00000010 0000 2b5c 5757 3a14 331f 1b23 0315 1d18
0x00000020 222a 2330 2b31 2e2a 1714 200d 1512 383d
0x00000030 1e1a 181b 0a10 1a21 2a36 281e 1d1c 0e11
0x00000040 1b2a 2f22 2229 181e 231e 181c 1913 262b
0x00000050 2b30 4741 422f 382a 1e22 0f17 0f10 3913

You can limit zooming to a range of bytes instead of the whole bytespace. Change zoom.from and
zoom.to eval variables:

[0x00003a04]> e? zoom.
zoom.byte: Zoom callback to calculate each byte (See pz? for help)
zoom.from: Zoom start address
zoom.in: Specify boundaries for zoom
zoom.maxsz: Zoom max size of block
zoom.to: Zoom end address
[0x00003a04]> e zoom.
zoom.byte = h
zoom.from = 0
zoom.in = io.map
zoom.maxsz = 512
zoom.to = 0

81
Yank/Paste

Yank/Paste
Radare2 has an internal clipboard to save and write portions of memory loaded from the current io
layer.

This clipboard can be manipulated with the y command.

The two basic operations are

copy (yank)
paste

The yank operation will read N bytes (specified by the argument) into the clipboard. We can later use
the yy command to paste what we read before into a file.

You can yank/paste bytes in visual mode selecting them with the cursor mode ( Vc ) and then using the
y and Y key bindings which are aliases for y and yy commands of the command-line interface.

[0x00000000]> y?
|Usage: y[ptxy] [len] [[@]addr] # See wd? for memcpy, same as 'yf'.
| y show yank buffer information (srcoff len bytes)
| y 16 copy 16 bytes into clipboard
| y 16 0x200 copy 16 bytes into clipboard from 0x200
| y 16 @ 0x200 copy 16 bytes into clipboard from 0x200
| yz [len] copy string (from current block) into clipboard
| yp print contents of clipboard
| yx print contents of clipboard in hexadecimal
| ys print contents of clipboard as string
| yt 64 0x200 copy 64 bytes from current seek to 0x200
| ytf file dump the clipboard to given file
| yf 64 0x200 copy 64 bytes from 0x200 from file
| yfa file copy copy all bytes from file (opens w/ io)
| yy 0x3344 paste clipboard

Sample session:

[0x00000000]> s 0x100 ; seek at 0x100

[0x00000100]> y 100 ; yanks 100 bytes from here
[0x00000200]> s 0x200 ; seek 0x200
[0x00000200]> yy ; pastes 100 bytes

82
Yank/Paste

You can perform a yank and paste in a single line by just using the yt command (yank-to). The syntax
is as follows:

[0x4A13B8C0]> x
offset 0 1 2 3 4 5 6 7 8 9 A B 0123456789AB
0x4A13B8C0, 89e0 e839 0700 0089 c7e8 e2ff ...9........
0x4A13B8CC, ffff 81c3 eea6 0100 8b83 08ff ............
0x4A13B8D8, ffff 5a8d 2484 29c2 ..Z.$.).

[0x4A13B8C0]> yt 8 0x4A13B8CC @ 0x4A13B8C0

[0x4A13B8C0]> x
offset 0 1 2 3 4 5 6 7 8 9 A B 0123456789AB
0x4A13B8C0, 89e0 e839 0700 0089 c7e8 e2ff ...9........
0x4A13B8CC, 89e0 e839 0700 0089 8b83 08ff ...9........
0x4A13B8D8, ffff 5a8d 2484 29c2 ..Z.$.).

83
Comparing Bytes

Comparing Bytes
For most generic reverse engineering tasks like finding the differences between two binary files, which
bytes has changed, find differences in the graphs of the code analysis results, and other diffing
operations you can just use radiff2:

$ radiff2 -h

Inside r2, the functionalities exposed by radiff2 are available with the c command.

c (short for "compare") allows you to compare arrays of bytes from different sources. The command

accepts input in a number of formats and then compares it against values found at current seek position.

[0x00404888]> c?
|Usage: c[?dfx] [argument] # Compare
| c [string] Compare a plain with escaped chars string
| c* [string] Same as above, but printing r2 commands
| c4 [value] Compare a doubleword from a math expression
| c8 [value] Compare a quadword from a math expression
| cat [file] Show contents of file (see pwd, ls)
| cc [at] Compares in two hexdump columns of block size
| ccc [at] Same as above, but only showing different lines
| ccd [at] Compares in two disasm columns of block size
| cf [file] Compare contents of file at current seek
| cg[?] [o] [file] Graphdiff current file and [file]
| cu[?] [addr] @at Compare memory hexdumps of $$ and dst in unified diff
| cud [addr] @at Unified diff disasm from $$ and given address
| cv[1248] [hexpairs] @at Compare 1,2,4,8-byte value
| cV[1248] [addr] @at Compare 1,2,4,8-byte address contents
| cw[?] [us?] [...] Compare memory watchers
| cx [hexpair] Compare hexpair string (use '.' as nibble wildcard)
| cx* [hexpair] Compare hexpair string (output r2 commands)
| cX [addr] Like 'cc' but using hexdiff output
| cd [dir] chdir
| cl|cls|clear Clear screen, (clear0 to goto 0, 0 only)

To compare memory contents at current seek position against a given string of values, use cx :

84
Comparing Bytes

[0x08048000]> p8 4
7f 45 4c 46

[0x08048000]> cx 7f 45 90 46
Compare 3/4 equal bytes
0x00000002 (byte=03) 90 ' ' -> 4c 'L'
[0x08048000]>

Another subcommand of the c command is cc which stands for "compare code". To compare a byte
sequence with a sequence in memory:

[0x4A13B8C0]> cc 0x39e8e089 @ 0x4A13B8C0

To compare contents of two functions specified by their names:

[0x08049A80]> cc sym.main2 @ sym.main

c8 compares a quadword from the current seek (in the example below, 0x00000000) against a math

expression:

[0x00000000]> c8 4

Compare 1/8 equal bytes (0%)

0x00000000 (byte=01) 7f ' ' -> 04 ' '
0x00000001 (byte=02) 45 'E' -> 00 ' '
0x00000002 (byte=03) 4c 'L' -> 00 ' '

The number parameter can, of course, be math expressions which use flag names and anything allowed
in an expression:

[0x00000000]> cx 7f469046

Compare 2/4 equal bytes

0x00000001 (byte=02) 45 'E' -> 46 'F'
0x00000002 (byte=03) 4c 'L' -> 90 ' '

You can use the compare command to find differences between a current block and a file previously
dumped to a disk:

85
Comparing Bytes

r2 /bin/true
[0x08049A80]> s 0
[0x08048000]> cf /bin/true
Compare 512/512 equal bytes

86
SDB

SDB
SDB stands for String DataBase. It's a simple key-value database that only operates with strings created
by pancake. It is used in many parts of r2 to have a disk and in-memory database which is small and fast
to manage using it as a hashtable on steroids.

SDB is a simple string key/value database based on djb’s cdb disk storage and supports JSON and
arrays introspection.

There’s also the sdbtypes: a vala library that implements several data structures on top of an sdb or a
memcache instance.

SDB supports:

namespaces (multiple sdb paths)

atomic database sync (never corrupted)
bindings for vala, luvit, newlisp and nodejs
commandline frontend for sdb databases
memcache client and server with sdb backend
arrays support (syntax sugar)
json parser/getter

Usage example
Let's create a database!

$ sdb d hello=world
$ sdb d hello
world

Using arrays:

87
SDB

$ sdb - '[]list=1,2' '[0]list' '[0]list=foo' '[]list' '[+1]list=bar'

1
foo
2
foo
bar
2

Let's play with json:

$ sdb d g='{"foo":1,"bar":{"cow":3}}'
$ sdb d g?bar.cow
3
$ sdb - user='{"id":123}' user?id=99 user?id
99

Using the command line without any disk database:

$ sdb - foo=bar foo a=3 +a -a

bar
4
3

$ sdb -
foo=bar
foo
bar
a=3
+a
4
-a
3

Remove the database

$ rm -f d

So what ?
So, you can now do this inside your radare2 sessions!

Let's take a simple binary, and check what is already sdbized.

88
SDB

$ cat test.c
int main(){
puts("Hello world\n");
}
$ gcc test.c -o test

$ r2 -A ./test
[0x08048320]> k **
bin
anal
syscall
debug

[0x08048320]> k bin/**
fd.6
[0x08048320]> k bin/fd.6/*
archs=0:0:x86:32

The file corresponding to the sixth file descriptor is a x86_32 binary.

[0x08048320]> k anal/meta/*
meta.s.0x80484d0=12,SGVsbG8gd29ybGQ=
[...]
[0x08048320]> ?b64- SGVsbG8gd29ybGQ=
Hello world

Strings are stored encoded in base64.

More Examples
List namespaces

k **

List sub-namespaces

k anal/**

89
SDB

List keys

k *
k anal/*

Set a key

k foo=bar

Get the value of a key

k foo

List all syscalls

k syscall/*~^0x

List all comments

k anal/meta/*~.C.

Show a comment at given offset:

k %anal/meta/[1]meta.C.0x100005000

90
Visual mode

Visual Mode
The visual mode is a more user-friendly interface alternative to radare2's command-line prompt. It
allows easy navigation, has a cursor mode for selecting bytes, and offers numerous key bindings to
simplify debugger use. To enter visual mode, use V command. To exit from it back to command line,
press q .

Navigation
Navigation can be done using HJKL or arrow keys and PgUp/PgDown keys. It also understands usual
Home/End keys. Like in Vim the movements can be repeated by preceding the navigation key with the
number, for example 5j will move down for 5 lines, or 2l will move 2 characters right.

print modes aka panels

91
Visual mode

The Visual mode uses "print modes" which are basically different panel that you can rotate. By default
those are:

↻ Hexdump panel -> Disassembly panel → Debugger panel → Hexadecimal words dump panel
→ Hex-less hexdump panel → Op analysis color map panel → Annotated hexdump panel ↺.

Notice that the top of the panel contains the command which is used, for example for the disassembly
panel:

[0x00404890 16% 120 /bin/ls]> pd $r @ entry0

Getting Help
To see help on all key bindings defined for visual mode, press ? :

Visual mode help:

? show this help
?? show the user-friendly hud
% in cursor mode finds matching pair, or toggle autoblocksz
@ redraw screen every 1s (multi-user view)
^ seek to the begining of the function
! enter into the visual panels mode
_ enter the flag/comment/functions/.. hud (same as VF_)
= set cmd.vprompt (top row)
| set cmd.cprompt (right column)
. seek to program counter
\ toggle visual split mode
" toggle the column mode (uses pC..)
/ in cursor mode search in current block
:cmd run radare command
;[-]cmt add/remove comment
0 seek to beginning of current function
[1-9] follow jmp/call identified by shortcut (like ;[1])
,file add a link to the text file
/*+-[] change block size, [] = resize hex.cols
</> seek aligned to block size (seek cursor in cursor mode)
a/A (a)ssemble code, visual (A)ssembler
b browse symbols, flags, configurations, classes, ...
B toggle breakpoint
c/C toggle (c)ursor and (C)olors
d[f?] define function, data, code, ..
D enter visual diff mode (set diff.from/to
e edit eval configuration variables
f/F set/unset or browse flags. f- to unset, F to browse, ..
gG go seek to begin and end of file (0-$s)

92
Visual mode

hjkl move around (or HJKL) (left-down-up-right)

i insert hex or string (in hexdump) use tab to toggle
mK/'K mark/go to Key (any key)
M walk the mounted filesystems
n/N seek next/prev function/flag/hit (scr.nkey)
o go/seek to given offset
O toggle asm.pseudo and asm.esil
p/P rotate print modes (hex, disasm, debug, words, buf)
q back to radare shell
r refresh screen / in cursor mode browse comments
R randomize color palette (ecr)
sS step / step over
t browse types
T enter textlog chat console (TT)
uU undo/redo seek
v visual function/vars code analysis menu
V (V)iew graph using cmd.graph (agv?)
wW seek cursor to next/prev word
xX show xrefs/refs of current function from/to data/code
yY copy and paste selection
z fold/unfold comments in disassembly
Z toggle zoom mode
Enter follow address of jump/call
Function Keys: (See 'e key.'), defaults to:
F2 toggle breakpoint
F4 run to cursor
F7 single step
F8 step over
F9 continue

93
Visual Disassembly

Visual Disassembly

Navigation
Move within the Disassembly using arrow keys or hjkl . Use o to seek directly to a flag or an offset,
type it when requested by the prompt: [offset]> . Follow a jump or a call using the number of your
keyboard [0-9] and the number on the right in disassembly to follow a call or a jump. In this example
typing 1 on the keyboard would follow the call to sym.imp.__libc_start_main and therefore, seek
at the offset of this symbol.

0x00404894 e857dcffff call sym.imp.__libc_start_main ;[1]

Seek back to the previous location using u , U will allow you to redo the seek.

d as define

d can be used to change the type of data of the current block, several basic types/structures are

available as well as more advanced one using pf template:

d → ...
0x004048f7 48c1e83f shr rax, 0x3f
d → b
0x004048f7 .byte 0x48
d → B
0x004048f7 .word 0xc148
d → d
0x004048f7 hex length=165 delta=0
0x004048f7 48c1 e83f 4801 c648 d1fe 7415 b800 0000
...

To improve code readability you can change how radare2 presents numerical values in disassembly, by
default most of disassembly display numerical value as hexadecimal. Sometimes you would like to view
it as a decimal, binary or even custom defined constant. To change value format you can use d
following by i then choose what base to work in, this is the equivalent to ahi :

94
Visual Disassembly

d → i → ...
0x004048f7 48c1e83f shr rax, 0x3f
d → i → 10
0x004048f7 48c1e83f shr rax, 63
d → i → 2
0x004048f7 48c1e83f shr rax, '?'

Usage of the Cursor for Inserting/Patching...

Remember that, to be able to actually edit files loaded in radare2, you have to start it with the -w
option. Otherwise a file is opened in read-only mode.

Pressing lowercase c toggles the cursor mode. When this mode is active, the currently selected byte
(or byte range) is highlighted.

The cursor is used to select a range of bytes or simply to point to a byte. You can use the cursor to create
a named flag at specifc location. To do so, seek to the required position, then press f and enter a name
for a flag. If the file was opened in write mode using the -w flag or the o+ command, you can also
use the cursor to overwrite a selected range with new values. To do so, select a range of bytes (with
HJKL and SHIFT key pressed), then press i and enter the hexpair values for the new data. The data
will be repeated as needed to fill the range selected. For example:

<select 10 bytes in visual mode using SHIFT+HJKL>

The 10 bytes you have selected will be changed to "12 34 12 34 12 ...".

The Visual Assembler is a feature that provides a live-preview while you type in new instructions to
patch into the disassembly. To use it, seek or place the cursor at the wanted location and hit the 'A' key.
To provide multiple instructions, separate them with semicolons, ; .

95
Visual Disassembly

XREF
When radare2 has discovered a XREF during the analysis, it will show you the information in the
Visual Disassembly using XREF tag:

; DATA XREF from 0x00402e0e (unk)

str.David_MacKenzie:

To see where this string is called, press x , if you want to jump to the location where the data is used
then press the corresponding number [0-9] on your keyboard. (This functionality is similar to axt )

X corresponds to the reverse operation aka axf .

Function Argument display

To enable this vew use this config var e dbg.funcarg = true

96
Visual Disassembly

Add a comment
To add a comment press ; .

Type other commands

Quickly type commands using : .

Search
97
Visual Disassembly

/ : allows highlighting of strings in the current display. :cmd allows you to use one of the "/?"

commands that perform more specialized searches.

The HUDS
The "UserFriendly HUD"
The "UserFriendly HUD" can be accessed using the ?? key-combination. This HUD acts as an
interactive Cheat Sheet that one can use to more easily find and execute commands. This HUD is
particularly useful for new-comers. For experienced users, the other HUDS which are more activity-
specific may be more useful.

The "flag/comment/functions/.. HUD"

This HUD can be displayed using the _ key, it shows a list of all the flags defined and lets you jump
to them. Using the keyboard you can quickly filter the list down to a flag that contains a specific pattern.

Tweaking the Disassembly

The disassembly's look-and-feel is controlled using the "asm.* configuration keys, which can be
changed using the e command. All configuration keys can also be edited through the Visual
Configuration Editor.

Visual Configuration Editor

This HUD can be accessed using the e key in visual mode. The editor allows you to easily examine
and change radare2's configuration. For example, if you want to change something about the
disassembly display, select asm from the list, navigate to the item you wish to modify it, then select it
by hitting Enter . If the item is a boolean variable, it will toggle, otherwise you will be prompted to
provide a new value.

98
Visual Disassembly

Example switch to pseudo disassembly:

99
Visual Disassembly

100
Visual Disassembly

Following are some example of eval variable related to disassembly.

101
Visual Disassembly

Examples
asm.arch: Change Architecture && asm.bits: Word size in bits
at assembler
You can view the list of all arch using e asm.arch=?

e asm.arch = dalvik
0x00404870 31ed4989 cmp-long v237, v73, v137
0x00404874 d15e4889 rsub-int v14, v5, 0x8948
0x00404878 e24883e4 ushr-int/lit8 v72, v131, 0xe4
0x0040487c f0505449c7c0 +invoke-object-init-range {}, method+18772 ;[0]
0x00404882 90244100 add-int v36, v65, v0

e asm.bits = 16
0000:4870 31ed xor bp, bp
0000:4872 49 dec cx
0000:4873 89d1 mov cx, dx
0000:4875 5e pop si
0000:4876 48 dec ax
0000:4877 89e2 mov dx, sp

This latest operation can also be done using & in Visual mode.

asm.pseudo: Enable pseudo syntax

e asm.pseudo = true
0x00404870 31ed ebp = 0
0x00404872 4989d1 r9 = rdx
0x00404875 5e pop rsi
0x00404876 4889e2 rdx = rsp
0x00404879 4883e4f0 rsp &= 0xfffffffffffffff0

asm.syntax: Select assembly syntax (intel, att, masm...)

e asm.syntax = att
0x00404870 31ed xor %ebp, %ebp
0x00404872 4989d1 mov %rdx, %r9
0x00404875 5e pop %rsi
0x00404876 4889e2 mov %rsp, %rdx
0x00404879 4883e4f0 and $0xfffffffffffffff0, %rsp

102
Visual Disassembly

asm.describe: Show opcode description

e asm.describe = true
0x00404870 xor ebp, ebp ; logical exclusive or
0x00404872 mov r9, rdx ; moves data from src to dst
0x00404875 pop rsi ; pops last element of stack and stores the result in argumen
t
0x00404876 mov rdx, rsp ; moves data from src to dst
0x00404879 and rsp, -0xf ; binary and operation between src and dst, stores result on
dst

103
Visual Assembler

Visual Assembler
You can use Visual Mode to assemble code using A . For example let's replace the push by a jmp :

Notice the preview of the disassembly and arrows:

104
Visual Assembler

You need to open the file in writing mode ( r2 -w or oo+ ) in order to patch the file. You can also use
the cache mode: e io.cache = true and wc? .

Remember that patching files in debug mode only patch the memory not the file.

105
Visual Configuration Editor

Visual Configuration Editor

Ve or e in visual mode allows you to edit radare2 configuration visually. For example, if you want

to change the assembly display just select asm in the list and choose your assembly display flavor.

106
Visual Configuration Editor

Example switch to pseudo disassembly:

107
Visual Configuration Editor

108
Visual Panels

Visual Panels

Concept
Visual Panels is characterized by the following core functionalities:

1. Split Screen
2. Display multiple screens such as Symbols, Registers, Stack, as well as custom panels
3. Menu will cover all those commonly used commands for you so that you don't have to memorize
any of them

CUI met some useful GUI as the menu, that is Visual Panels.

Panels can be accessed from visual mode by using ! .

Overview

Commands

109
Visual Panels

|Visual Ascii Art Panels:

Basic Usage
Use tab to move around the panels until you get to the targeted panel. Then, use hjkl , just like in
vim, to scroll the panel you are currently on. Use S and s to step over/in, and all the panels should
be updated dynamically while you are debugging. Either in the Registers or Stack panels, you can edit

110
Visual Panels

the values by inserting hex. This will be explained later. While hitting tab can help you moving
between panels, it is highly recommended to use m to open the menu. As usual, you can use hjkl to
move around the menu and will find tons of useful stuff there.

Split Screen
| is for the vertical and - is for the horizontal split. You can delete any panel by pressing X .

Split panels can be resized from Window Mode, which is accessed with w .

Window Mode Commands

Edit Values
Either in the Register or Stack panel, you can edit the values. Use c to activate cursor mode and you
can move the cursor by pressing hjkl , as usual. Then, hit i , just like the insert mode of vim, to
insert a value.

111
Searching bytes

Searching for Bytes

The radare2 search engine is based on work done by esteve, plus multiple features implemented on top
of it. It supports multiple keyword searches, binary masks, and hexadecimal values. It automatically
creates flags for search hit locations ease future referencing.

Search is initiated by / command.

112
Searching bytes

[0x00000000]> /?
|Usage: /[!bf] [arg]Search stuff (see 'e??search' for options)
|Use io.va for searching in non virtual addressing spaces
| / foo\x00 search for string 'foo\0'
| /j foo\x00 search for string 'foo\0' (json output)
| /! ff search for first occurrence not matching, command modifier
| /!x 00 inverse hexa search (find first byte != 0x00)
| /+ /bin/sh construct the string with chunks
| // repeat last search
| /a jmp eax assemble opcode and search its bytes
| /A jmp find analyzed instructions of this type (/A? for help)
| /b search backwards, command modifier, followed by other command
| /B search recognized RBin headers
| /c jmp [esp] search for asm code matching the given string
| /ce rsp,rbp search for esil expressions matching
| /C[ar] search for crypto materials
| /d 101112 search for a deltified sequence of bytes
| /e /E.F/i match regular expression
| /E esil-expr offset matching given esil expressions %%= here
| /f search forwards, command modifier, followed by other command
| /F file [off] [sz] search contents of file with offset and size
| /g[g] [from] find all graph paths A to B (/gg follow jumps, see search.coun
t and
anal.depth)
| /h[t] [hash] [len] find block matching this hash. See ph
| /i foo search for string 'foo' ignoring case
| /m magicfile search for matching magic file (use blocksize)
| /M search for known filesystems and mount them automatically
| /o [n] show offset of n instructions backward
| /O [n] same as /o, but with a different fallback if anal cannot be us
ed
| /p patternsize search for pattern of given size
| /P patternsize search similar blocks
| /r[erwx][?] sym.printf analyze opcode reference an offset (/re for esil)
| /R [grepopcode] search for matching ROP gadgets, semicolon-separated
| /s search for all syscalls in a region (EXPERIMENTAL)
| /v[1248] value look for an `cfg.bigendian` 32bit value
| /V[1248] min max look for an `cfg.bigendian` 32bit value in range
| /w foo search for wide string 'f\0o\0o\0'
| /wi foo search for wide string ignoring case 'f\0o\0o\0'
| /x ff..33 search for hex string ignoring some nibbles
| /x ff0033 search for hex string
| /x ff43:ffd0 search for hexpair with mask
| /z min max search for strings of given size

Because everything is treated as a file in radare2, it does not matter whether you search in a socket, a
remote device, in process memory, or a file.

113
Searching bytes

114
Basic Searches

Basic Search
A basic search for a plain text string in a file would be something like:

$ r2 -q -c "/ lib" /bin/ls

Searching 3 bytes from 0x00400000 to 0x0041ae08: 6c 69 62
hits: 9
0x00400239 hit0_0 "lib64/ld-linux-x86-64.so.2"
0x00400f19 hit0_1 "libselinux.so.1"
0x00400fae hit0_2 "librt.so.1"
0x00400fc7 hit0_3 "libacl.so.1"
0x00401004 hit0_4 "libc.so.6"
0x004013ce hit0_5 "libc_start_main"
0x00416542 hit0_6 "libs/"
0x00417160 hit0_7 "lib/xstrtol.c"
0x00417578 hit0_8 "lib"

As can be seen from the output above, radare2 generates a "hit" flag for every entry found. You can then
use the ps command to see the strings stored at the offsets marked by the flags in this group, and they
will have names of the form hit0_<index> :

[0x00404888]> / ls
...
[0x00404888]> ps @ hit0_0
lseek

You can search for wide-char strings (e.g., unicode letters) using the /w command:

[0x00000000]> /w Hello
0 results found.

To perform a case-insensitive search for strings use /i :

[0x0040488f]> /i Stallman
Searching 8 bytes from 0x00400238 to 0x0040488f: 53 74 61 6c 6c 6d 61 6e
[# ]hits: 004138 < 0x0040488f hits = 0

It is possible to specify hexadecimal escape sequences in the search string by prepending them with
"\x":

115
Basic Searches

[0x00000000]> / \x7FELF

But, if you are searching for a string of hexadecimal values, you're probably better of using the /x
command:

[0x00000000]> /x 7F454C46

Once the search is done, the results are stored in the searches flag space.

[0x00000000]> fs
0 0 . strings
1 0 . symbols
2 6 . searches

[0x00000000]> f
0x00000135 512 hit0_0
0x00000b71 512 hit0_1
0x00000bad 512 hit0_2
0x00000bdd 512 hit0_3
0x00000bfb 512 hit0_4
0x00000f2a 512 hit0_5

To remove "hit" flags after you do not need them anymore, use the f- hit* command.

Often, during long search sessions, you will need to launch the latest search more than once. You can
use the // command to repeat the last search.

[0x00000f2a]> // ; repeat last search

116
Configurating the Search

Configuring Search Options

The radare2 search engine can be configured through several configuration variables, modifiable with
the e command.

e cmd.hit = x ; radare2 command to execute on every search hit

e search.distance = 0 ; search string distance
e search.in = [foo] ; pecify search boundarie. Supported values are listed under e sea
rch.in=??
e search.align = 4 ; only show search results aligned by specified boundary.
e search.from = 0 ; start address
e search.to = 0 ; end address
e search.asmstr = 0 ; search for string instead of assembly
e search.flags = true ; if enabled, create flags on hits

The search.align variable is used to limit valid search hits to certain alignment. For example, with e
search.align=4 you will see only hits found at 4-bytes aligned offsets.

The search.flags boolean variable instructs the search engine to flag hits so that they can be
referenced later. If a currently running search is interrupted with Ctrl-C keyboard sequence, current
search position is flagged with search_stop .

117
Pattern Search

Pattern Matching Search

The /p command allows you to apply repeated pattern searches on IO backend storage. It is possible
to identify repeated byte sequences without explicitly specifying them. The only command's parameter
sets minimum detectable pattern length. Here is an example:

[0x00000000]> /p 10

This command output will show different patterns found and how many times each of them is
encountered.

118
Automation

Search Automation
The cmd.hit configuration variable is used to define a radare2 command to be executed when a
matching entry is found by the search engine. If you want to run several commands, separate them with
; . Alternatively, you can arrange them in a separate script, and then invoke it as a whole with .

script-file-name command. For example:

[0x00404888]> e cmd.hit = p8 8
[0x00404888]> / lib
Searching 3 bytes from 0x00400000 to 0x0041ae08: 6c 69 62
hits: 9
0x00400239 hit4_0 "lib64/ld-linux-x86-64.so.2"
31ed4989d15e4889
0x00400f19 hit4_1 "libselinux.so.1"
31ed4989d15e4889
0x00400fae hit4_2 "librt.so.1"
31ed4989d15e4889
0x00400fc7 hit4_3 "libacl.so.1"
31ed4989d15e4889
0x00401004 hit4_4 "libc.so.6"
31ed4989d15e4889
0x004013ce hit4_5 "libc_start_main"
31ed4989d15e4889
0x00416542 hit4_6 "libs/"
31ed4989d15e4889
0x00417160 hit4_7 "lib/xstrtol.c"
31ed4989d15e4889
0x00417578 hit4_8 "lib"
31ed4989d15e4889

119
Backward Search

Searching Backwards
Sometimes you want to find a keyword backwards. This is, before the current offset, to do this you can
seek back and search forward by adding some search.from/to restrictions, or use the /b command.

[0x100001200]> / nop
0x100004b15 hit0_0 .STUWabcdefghiklmnopqrstuvwxbin/ls.
0x100004f50 hit0_1 .STUWabcdefghiklmnopqrstuwx1] [file .
[0x100001200]> /b nop
[0x100001200]> s 0x100004f50p
[0x100004f50]> /b nop
0x100004b15 hit2_0 .STUWabcdefghiklmnopqrstuvwxbin/ls.
[0x100004f50]>

Note that /b is doing the same as / , but backward, so what if we want to use /x backward? We
can use /bx , and the same goes for other search subcommands:

[0x100001200]> /x 90
0x100001a23 hit1_0 90
0x10000248f hit1_1 90
0x1000027b2 hit1_2 90
0x100002b2e hit1_3 90
0x1000032b8 hit1_4 90
0x100003454 hit1_5 90
0x100003468 hit1_6 90
0x10000355b hit1_7 90
0x100003647 hit1_8 90
0x1000037ac hit1_9 90
0x10000389c hit1_10 90
0x100003c5c hit1_11 90

[0x100001200]> /bx 90
[0x100001200]> s 0x10000355b
[0x10000355b]> /bx 90
0x100003468 hit3_0 90
0x100003454 hit3_1 90
0x1000032b8 hit3_2 90
0x100002b2e hit3_3 90
0x1000027b2 hit3_4 90
0x10000248f hit3_5 90
0x100001a23 hit3_6 90
[0x10000355b]>

120
Backward Search

121
Search in Assembly

Assembler Search
If you want to search for a certain assembler opcodes, you can either use /c or /a commands.

The command /c jmp [esp] searches for the specified category of assembly mnemonic:

[0x00404888]> /c jmp qword [rdx]

f hit_0 @ 0x0040e50d # 2: jmp qword [rdx]
f hit_1 @ 0x00418dbb # 2: jmp qword [rdx]
f hit_2 @ 0x00418fcb # 3: jmp qword [rdx]
f hit_3 @ 0x004196ab # 6: jmp qword [rdx]
f hit_4 @ 0x00419bf3 # 3: jmp qword [rdx]
f hit_5 @ 0x00419c1b # 3: jmp qword [rdx]
f hit_6 @ 0x00419c43 # 3: jmp qword [rdx]

The command /a jmp eax assembles a string to machine code, and then searches for the resulting
bytes:

[0x00404888]> /a jmp eax

hits: 1
0x004048e7 hit3_0 ffe00f1f8000000000b8

122
Searching for AES Keys

Searching for AES Keys

Thanks to Victor Muñoz, radare2 now has support of the algorithm he developed, capable of finding
expanded AES keys with /Ca command. It searches from current seek position up to the
search.distance limit, or until end of file is reached. You can interrupt current search by pressing

Ctrl-C . For example, to look for AES keys in physical memory of your system:

$ sudo r2 /dev/mem
[0x00000000]> /Ca
0 AES keys found

123
Disassembling

Disassembling
Disassembling in radare is just a way to represent an array of bytes. It is handled as a special print mode
within p command.

In the old times, when the radare core was smaller, the disassembler was handled by an external rsc file.
That is, radare first dumped current block into a file, and then simply called objdump configured to
disassemble for Intel, ARM or other supported architectures.

It was a working and unix friendly solution, but it was inefficient as it repeated the same expensive
actions over and over, because there were no caches. As a result, scrolling was terribly slow.

So there was a need to create a generic disassembler library to support multiple plugins for different
architectures. We can list the current loaded plugins with

$ rasm2 -L

Or from inside radare2:

> e asm.arch=??

This was many years before capstone appeared. So r2 was using udis86 and olly disassemblers, many
gnu (from binutils).

Nowadays, the disassembler support is one of the basic features of radare. It now has many options,
endianness, including target architecture flavor and disassembler variants, among other things.

To see the disassembly, use the pd command. It accepts a numeric argument to specify how many
opcodes of current block you want to see. Most of the commands in radare consider the current block
size as the default limit for data input. If you want to disassemble more bytes, set a new block size using
the b command.

[0x00000000]> b 100 ; set block size to 100

[0x00000000]> pd ; disassemble 100 bytes
[0x00000000]> pd 3 ; disassemble 3 opcodes
[0x00000000]> pD 30 ; disassemble 30 bytes

124
Disassembling

The pD command works like pd but accepts the number of input bytes as its argument, instead of the
number of opcodes.

The "pseudo" syntax may be somewhat easier for a human to understand than the default assembler
notations. But it can become annoying if you read lots of code. To play with it:

[0x00405e1c]> e asm.pseudo = true

[0x00405e1c]> pd 3
; JMP XREF from 0x00405dfa (fcn.00404531)
0x00405e1c 488b9424a80. rdx = [rsp+0x2a8]
0x00405e24 64483314252. rdx ^= [fs:0x28]
0x00405e2d 4889d8 rax = rbx

[0x00405e1c]> e asm.syntax = intel

[0x00405e1c]> pd 3
; JMP XREF from 0x00405dfa (fcn.00404531)
0x00405e1c 488b9424a80. mov rdx, [rsp+0x2a8]
0x00405e24 64483314252. xor rdx, [fs:0x28]
0x00405e2d 4889d8 mov rax, rbx

[0x00405e1c]> e asm.syntax=att
[0x00405e1c]> pd 3
; JMP XREF from 0x00405dfa (fcn.00404531)
0x00405e1c 488b9424a80. mov 0x2a8(%rsp), %rdx
0x00405e24 64483314252. xor %fs:0x28, %rdx
0x00405e2d 4889d8 mov %rbx, %rax

125
Adding Metadata

Adding Metadata to Disassembly

The typical work involved in reversing binary files makes powerful annotation capabilities essential.
Radare offers multiple ways to store and retrieve such metadata.

By following common basic UNIX principles, it is easy to write a small utility in a scripting language
which uses objdump , otool or any other existing utility to obtain information from a binary and to
import it into radare. For example, take a look at idc2r.py shipped with radare2ida. To use it, invoke
it as idc2r.py file.idc > file.r2 . It reads an IDC file exported from an IDA Pro database and
produces an r2 script containing the same comments, names of functions and other data. You can import
the resulting 'file.r2' by using the dot . command of radare:

[0x00000000]> . file.r2

The . command is used to interpret Radare commands from external sources, including files and
program output. For example, to omit generation of an intermediate file and import the script directly
you can use this combination:

[0x00000000]> .!idc2r.py < file.idc

Please keep in mind that importing IDA Pro metadata from IDC dump is deprecated mechanism and
might not work in the future. The recommended way to do it - use python-idb-based ida2r2.py which
opens IDB files directly without IDA Pro installed.

The C command is used to manage comments and data conversions. You can define a range of
program's bytes to be interpreted as either code, binary data or string. It is also possible to execute
external code at every specified flag location in order to fetch some metadata, such as a comment, from
an external file or database.

There are many different metadata manipulation commands, here is the glimpse of all of them:

126
Adding Metadata

[0x00404cc0]> C?
|Usage: C[-LCvsdfm*?][*?] [...] # Metadata management
| C list meta info in human friendly form
| C* list meta info in r2 commands
| C[Chsdmf] list comments/hidden/strings/data/magic/formatted in huma
n friendly form
| C[Chsdmf]* list comments/hidden/strings/data/magic/formatted in r2 c
ommands
| C- [len] [[@]addr] delete metadata at given address range
| CL[-][*] [file:line] [addr] show or add 'code line' information (bininfo)
| CS[-][space] manage meta-spaces to filter comments, etc..
| CC[?] [-] [comment-text] [@addr] add/remove comment
| CC.[addr] show comment in current address
| CC! [@addr] edit comment with $EDITOR
| CCa[-at]|[at] [text] [@addr] add/remove comment at given address
| CCu [comment-text] [@addr] add unique comment
| Cv[bsr][?] add comments to args
| Cs[?] [-] [size] [@addr] add string
| Cz[@addr] add string (see Cs?)
| Ch[-] [size] [@addr] hide data
| Cd[-] [size] [repeat] [@addr]hexdump data array (Cd 4 10 == dword [10])
| Cf[?][-] [sz] [0|cnt][fmt] [a0 a1...] [@addr] format memory (see pf?)
| CF[sz] [fcn-sign..] [@addr] function signature
| Cm[-] [sz] [fmt..] [@addr] magic parse (see pm?)

Simply to add the comment to a particular line/address you can use Ca command:

[0x00000000]> CCa 0x0000002 this guy seems legit

[0x00000000]> pd 2
0x00000000 0000 add [rax], al
; this guy seems legit
0x00000002 0000 add [rax], al

The C? family of commands lets you mark a range as one of several kinds of types. Three basic types
are: code (disassembly is done using asm.arch), data (an array of data elements) or string. Use the Cs
comand to define a string, use the Cd command for defining an array of data elements, and use the
Cf command to define more complex data structures like structs.

Annotating data types is most easily done in visual mode, using the "d" key, short for "data type
change". First, use the cursor to select a range of bytes (press c key to toggle cursor mode and use
HJKL keys to expand selection), then press 'd' to get a menu of possible actions/types. For example, to
mark the range as a string, use the 's' option from the menu. You can achieve the same result from the
shell using the Cs command:

127
Adding Metadata

[0x00000000]> f string_foo @ 0x800

[0x00000000]> Cs 10 @ string_foo

The Cf command is used to define a memory format string (the same syntax used by the pf
command). Here's an example:

[0x7fd9f13ae630]> Cf 16 2xi foo bar

[0x7fd9f13ae630]> pd
;-- rip:
0x7fd9f13ae630 format 2xi foo bar {
0x7fd9f13ae630 [0] {
foo : 0x7fd9f13ae630 = 0xe8e78948
bar : 0x7fd9f13ae634 = 14696
}
0x7fd9f13ae638 [1] {
foo : 0x7fd9f13ae638 = 0x8bc48949
bar : 0x7fd9f13ae63c = 571928325
}
} 16
0x7fd9f13ae633 e868390000 call 0x7fd9f13b1fa0
0x7fd9f13ae638 4989c4 mov r12, rax

The [sz] argument to Cf is used to define how many bytes the struct should take up in the
disassembly, and is completely independent from the size of the data structure defined by the format
string. This may seem confusing, but has several uses. For example, you may want to see the formatted
structure displayed in the disassembly, but still have those locations be visible as offsets and with raw
bytes. Sometimes, you find large structures, but only identified a few fields, or only interested in
specific fields. Then, you can tell r2 to display only those fields, using the format string and using 'skip'
fields, and also have the disassembly continue after the entire structure, by giving it full size using the
sz argument.

Using Cf , it's easy to define complex structures with simple oneliners. See pf? for more
information. Remember that all these C commands can also be accessed from the visual mode by
pressing the d (data conversion) key. Note that unlike t commands Cf doesn't change analysis
results. It is only a visual boon.

Sometimes just adding a single line of comments is not enough, in this case radare2 allows you to create
a link for a particular text file. You can use it with CC, command or by pressing , key in the visual
mode. This will open an $EDITOR to create a new file, or if filename does exist, just will create a link.
It will be shown in the disassembly comments:

128
Adding Metadata

[0x00003af7 11% 290 /bin/ls]> pd $r @ main+55 # 0x3af7

│0x00003af7 call sym.imp.setlocale ;[1] ; ,(locale-help.txt) ; char *setlocale(i
nt category, const char *locale)
│0x00003afc lea rsi, str.usr_share_locale ; 0x179cc ; "/usr/share/locale"
│0x00003b03 lea rdi, [0x000179b2] ; "coreutils"
│0x00003b0a call sym.imp.bindtextdomain ;[2] ; char *bindtextdomain(char *domainname,
char *dirname)

Note ,(locale-help.txt) appeared in the comments, if we press , again in the visual mode, it will
open the file. Using this mechanism we can create a long descriptions of some particular places in
disassembly, link datasheets or related articles.

129
ESIL

ESIL
ESIL stands for 'Evaluable Strings Intermediate Language'. It aims to describe a Forth)-like
representation for every target CPU opcode semantics. ESIL representations can be evaluated
(interpreted) in order to emulate individual instructions. Each command of an ESIL expression is
separated by a comma. Its virtual machine can be described as this:

while ((word=haveCommand())) {
if (word.isOperator()) {
esilOperators[word](esil);
} else {
esil.push (word);
}
nextCommand();
}

As we can see ESIL uses a stack-based interpreter similar to what is commonly used for calculators.
You have two categories of inputs: values and operators. A value simply gets pushed on the stack, an
operator then pops values (its arguments if you will) off the stack, performs its operation and pushes its
results (if any) back on. We can think of ESIL as a post-fix notation of the operations we want to do.

So let's see an example:

4,esp,-=,ebp,esp,=[4]

Can you guess what this is? If we take this post-fix notation and transform it back to in-fix we get

esp -= 4
4bytes(dword) [esp] = ebp

We can see that this corresponds to the x86 instruction push ebp ! Isn't that cool? The aim is to be able
to express most of the common operations performed by CPUs, like binary arithmetic operations,
memory loads and stores, processing syscalls. This way if we can transform the instructions to ESIL we
can see what a program does while it is running even for the most cryptic architectures you definitely
don't have a device to debug on for.

Using ESIL
130
ESIL

r2's visual mode is great to inspect the ESIL evaluations.

There are 2 environment variables that are important for watching what a program does:

[0x00000000]> e emu.str = true

asm.emu tells r2 if you want ESIL information to be displayed. If it is set to true, you will see

comments appear to the right of your disassembly that tell you how the contents of registers and
memory addresses are changed by the current instruction. For example, if you have an instruction that
subtracts a value from a register it tells you what the value was before and what it becomes after. This is
super useful so you don't have to sit there yourself and track which value goes where.

One problem with this is that it is a lot of information to take in at once and sometimes you simply don't
need it. r2 has a nice compromise for this. That is what the emu.str variable is for ( asm.emustr on
<= 2.2). Instead of this super verbose output with every register value, this only adds really useful
information to the output, e.g., strings that are found at addresses a program uses or whether a jump is
likely to be taken or not.

The third important variable is asm.esil . This switches your disassembly to no longer show you the
actual disassembled instructions, but instead now shows you corresponding ESIL expressions that
describe what the instruction does. So if you want to take a look at how instructions are expressed in
ESIL simply set "asm.esil" to true.

[0x00000000]> e asm.esil = true

In visual mode you can also toggle this by simply typing O .

ESIL Commands
"ae" : Evaluate ESIL expression.

[0x00000000]> "ae 1,1,+"

0x2
[0x00000000]>

"aes" : ESIL Step.

131
ESIL

[0x00000000]> aes
[0x00000000]>10aes

"aeso" : ESIL Step Over.

[0x00000000]> aeso
[0x00000000]>10aeso

"aesu" : ESIL Step Until.

[0x00001000]> aesu 0x1035

ADDR BREAK
[0x00001019]>

"ar" : Show/modify ESIL registry.

[0x00001ec7]> ar r_00 = 0x1035

[0x00001ec7]> ar r_00
0x00001035
[0x00001019]>

ESIL Instruction Set

Here is the complete instruction set used by the ESIL VM:

ESIL
Operands Name Operation example
Opcode

TRAP src Trap Trap signal

$ src Syscall syscall

Get address of
Instruction current instruction
$$ src
address stack=instruction
address

stack = (dst ==
src) ;
== src,dst Compare
update_eflags(dst
- src)

stack = (dst < src) [0x0000000]> "ae 1,5,

Smaller <"
132
ESIL

< src,dst (signed update_eflags(dst 0x0

comparison) - src) > "ae 5,5"
0x0"

[0x0000000]> "ae 1,5,

stack = (dst <=
Smaller or <"
src) ;
<= src,dst Equal (signed 0x0
update_eflags(dst
comparison) > "ae 5,5"
- src)
0x1"

stack = (dst > src) > "ae 1,5,>"

Bigger (signed ; 0x1
> src,dst
comparison) update_eflags(dst > "ae 5,5,>"
- src) 0x0

stack = (dst >= > "ae 1,5,>="

Bigger or
src) ; 0x1
>= src,dst Equal (signed
update_eflags(dst > "ae 5,5,>="
comparison)
- src) 0x1

> "ae 1,1,<<"

0x2
<< src,dst Shift Left stack = dst << src
> "ae 2,1,<<"
0x4

> "ae 1,4,>>"

0x2
>> src,dst Shift Right stack = dst >> src
> "ae 2,4,>>"
0x1

> "ae 31,1,<<<"

0x80000000
<<< src,dst Rotate Left stack=dst ROL src
> "ae 32,1,<<<"
0x1

> "ae 1,1,>>>"

0x80000000
>>> src,dst Rotate Right stack=dst ROR src
> "ae 32,1,>>>"
0x1

> "ae 1,1,&"

0x1
> "ae 1,0,&"
0x0
& src,dst AND stack = dst & src
> "ae 0,1,&"
0x0
> "ae 0,0,&"
0x0

> "ae 1,1,|"

0x1

133
ESIL

> "ae 1,0,|"

0x1
| src,dst OR stack = dst | src > "ae 0,1,|"
0x1
> "ae 0,0,|"
0x0

> "ae 1,1,^"

0x0
> "ae 1,0,^"
0x1
^ src,dst XOR stack = dst ^src
> "ae 0,1,^"
0x1
> "ae 0,0,^"
0x0

> "ae 3,4,+"

0x7
+ src,dst ADD stack = dst + src
> "ae 5,5,+"
0xa

> "ae 3,4,-"

0x1
> "ae 5,5,-"
- src,dst SUB stack = dst - src
0x0
> "ae 4,3,-"
0xffffffffffffffff

> "ae 3,4,*"

0xc
* src,dst MUL stack = dst * src
> "ae 5,5,*"
0x19

> "ae 2,4,/"

0x2
> "ae 5,5,/"
/ src,dst DIV stack = dst / src
0x1
> "ae 5,9,/"
0x1

> "ae 2,4,%"

0x0
> "ae 5,5,%"
% src,dst MOD stack = dst % src
0x0
> "ae 5,9,%"
0x4

> "ae 1,!"

0x0
> "ae 4,!"
! src NEG stack = !!!src 0x0
134
ESIL

> "ae 0,!"

0x1

> ar r_00=0;ar r_00

0x00000000
> "ae r_00,++"
0x1
++ src INC stack = src++
> ar r_00
0x00000000
> "ae 1,++"
0x2

> ar r_00=5;ar r_00

0x00000005
> "ae r_00,--"
0x4
-- src DEC stack = src--
> ar r_00
0x00000005
> "ae 5,--"
0x4

> "ae 3,r_00,="

> aer r_00
0x00000003
= src,reg EQU reg = src
> "ae r_00,r_01,="
> aer r_01
0x00000003

> ar r_01=5;ar
r_00=0;ar r_00
0x00000000
> "ae r_01,r_00,+="
+= src,reg ADD eq reg = reg + src > ar r_00
0x00000005
> "ae 5,r_00,+="
> ar r_00
0x0000000a

> "ae r_01,r_00,-="

> ar r_00
0x00000004
-= src,reg SUB eq reg = reg - src
> "ae 3,r_00,-="
> ar r_00
0x00000001

> ar r_01=3;ar
r_00=5;ar r_00
0x00000005
> "ae r_01,r_00,*="
*= src,reg MUL eq reg = reg * src > ar r_00
0x0000000f

135
ESIL

> "ae 2,r_00,*="

> ar r_00
0x0000001e

> ar r_01=3;ar
r_00=6;ar r_00
0x00000006
> "ae r_01,r_00,/="
/= src,reg DIV eq reg = reg / src > ar r_00
0x00000002
> "ae 1,r_00,/="
> ar r_00
0x00000002

> ar r_01=3;ar
r_00=7;ar r_00
0x00000007
> "ae r_01,r_00,%="
> ar r_00
%= src,reg MOD eq reg = reg % src 0x00000001
> ar r_00=9;ar r_00
0x00000009
> "ae 5,r_00,%="
> ar r_00
0x00000004

> ar r_00=1;ar
r_01=1;ar r_01
0x00000001
> "ae r_00,r_01,<<="
<<= src,reg Shift Left eq reg = reg << src > ar r_01
0x00000002
> "ae 2,r_01,<<="
> ar r_01
0x00000008

> ar r_00=1;ar
r_01=8;ar r_01
0x00000008
> "ae r_00,r_01,>>="
>>= src,reg Shift Right eq reg = reg << src > ar r_01
0x00000004
> "ae 2,r_01,>>="
> ar r_01
0x00000001

> ar r_00=2;ar
r_01=6;ar r_01
0x00000006
> "ae r_00,r_01,&="
> ar r_01
136
ESIL

> ar r_01
&= src,reg AND eq reg = reg & src 0x00000002
> "ae 2,r_01,&="
> ar r_01
0x00000002
> "ae 1,r_01,&="
> ar r_01
0x00000000

> ar r_00=2;ar
r_01=1;ar r_01
0x00000001
> "ae r_00,r_01,|="
|= src,reg OR eq reg = reg | src > ar r_01
0x00000003
> "ae 4,r_01,|="
> ar r_01
0x00000007

> ar r_00=2;ar
r_01=0xab;ar r_01
0x000000ab
> "ae r_00,r_01,^="
^= src,reg XOR eq reg = reg ^ src > ar r_01
0x000000a9
> "ae 2,r_01,^="
> ar r_01
0x000000ab

> ar r_00=4;ar r_00

0x00000004
++= reg INC eq reg = reg + 1 > "ae r_00,++="
> ar r_00
0x00000005

> ar r_00=4;ar r_00

0x00000004
--= reg DEC eq reg = reg - 1 > "ae r_00,--="
> ar r_00
0x00000003

> ar r_00=4;ar r_00

0x00000004
> "ae r_00,!="
> ar r_00
!= reg NOT eq reg = !reg
0x00000000
> "ae r_00,!="
> ar r_00
0x00000001

---------------------------
--- --- --- ---
137
ESIL

> "ae
0xdeadbeef,0x10000,=
[4],"
=[]
> pxw 4@0x10000
=[*]
0x00010000
=[1]
src,dst poke *dst=src 0xdeadbeef ....
=[2]
=[4]
> "ae 0x0,0x10000,=
=[8]
[4],"

> pxw 4@0x10000

0x00010000
0x00000000

> w test@0x10000
[]
[*] > "ae 0x10000,[4],"
[1] 0x74736574
src peek stack=*src
[2]
[4] > ar r_00=0x10000
[8]
> "ae r_00,[4],"
0x74736574

|=[]
|=[1]
>
|=[2] reg nombre code
>
|=[4]
|=[8]

Swap two top

SWAP Swap SWAP
elements

Pick nth element

PICK n Pick from the top of the 2,PICK
stack

Pick nth element

RPICK m Reverse Pick from the base of 0,RPICK
the stack

Duplicate top
DUP Duplicate DUP
element in stack

If top element is a
reference
(register name,
138
ESIL

dereference it and
push its real value

CLEAR Clear Clear stack CLEAR

Stops ESIL
BREAK Break BREAK
emulation

Jumps to Nth
GOTO n Goto GOTO 5
ESIL word

Stops execution
(reason: ESIL
TODO To Do TODO
expression not
completed)

ESIL Flags
ESIL VM has an internal state flags that are read-only and can be used to export those values to the
underlying target CPU flags. It is because the ESIL VM always calculates all flag changes, while target
CPUs only update flags under certain conditions or at specific instructions.

Internal flags are prefixed with $ character.

z - zero flag, only set if the result of an operation is 0

b - borrow, this requires to specify from which bit (example: $b4 - checks if borro
w from bit 4)
c - carry, same like above (example: $c7 - checks if carry from bit 7)
o - overflow
p - parity
r - regsize ( asm.bits/8 )
s - sign
ds - delay slot state
jt - jump target
js - jump target set
[0-9]* - Used to set flags and registers without having any side effects,
i.e. setting esil_cur, esil_old and esil_lastsz.
(example: "$0,of,=" to reset the overflow flag)

Syntax and Commands

A target opcode is translated into a comma separated list of ESIL expressions.

xor eax, eax -> 0,eax,=,1,zf,=

139
ESIL

xor eax, eax -> 0,eax,=,1,zf,=

Memory access is defined by brackets operation:

mov eax, [0x80480] -> 0x80480,[],eax,=

Default operand size is determined by size of operation destination.

movb $0, 0x80480 -> 0,0x80480,=[1]

The ? operator uses the value of its argument to decide whether to evaluate the expression in curly
braces.

1. Is the value zero? -> Skip it.

2. Is the value non-zero? -> Evaluate it.

cmp eax, 123 -> 123,eax,==,$z,zf,=

jz eax -> zf,?{,eax,eip,=,}

If you want to run several expressions under a conditional, put them in curly braces:

zf,?{,eip,esp,=[],eax,eip,=,$r,esp,-=,}

Whitespaces, newlines and other chars are ignored. So the first thing when processing a ESIL program
is to remove spaces:

esil = r_str_replace (esil, " ", "", R_TRUE);

Syscalls need special treatment. They are indicated by '$' at the beginning of an expression. You can
pass an optional numeric value to specify a number of syscall. An ESIL emulator must handle syscalls.
See (r_esil_syscall).

Arguments Order for Non-associative

Operations
As discussed on IRC, the current implementation works like this:

140
ESIL

a,b,- b - a
a,b,/= b /= a

This approach is more readable, but it is less stack-friendly.

Special Instructions
NOPs are represented as empty strings. As it was said previously, syscalls are marked by '$' command.
For example, '0x80,$'. It delegates emulation from the ESIL machine to a callback which implements
syscalls for a specific OS/kernel.

Traps are implemented with the TRAP command. They are used to throw exceptions for invalid
instructions, division by zero, memory read error, or any other needed by specific architectures.

Quick Analysis
Here is a list of some quick checks to retrieve information from an ESIL string. Relevant information
will be probably found in the first expression of the list.

indexOf('[') -> have memory references

indexOf("=[") -> write in memory
indexOf("pc,=") -> modifies program counter (branch, jump, call)
indexOf("sp,=") -> modifies the stack (what if we found sp+= or sp-=?)
indexOf("=") -> retrieve src and dst
indexOf(":") -> unknown esil, raw opcode ahead
indexOf("$") -> accesses internal esil vm flags ex: $z
indexOf("$") -> syscall ex: 1,$
indexOf("TRAP") -> can trap
indexOf('++') -> has iterator
indexOf('--') -> count to zero
indexOf("?{") -> conditional
equalsTo("") -> empty string, aka nop (wrong, if we append pc+=x)

Common operations:

Check dstreg
Check srcreg
Get destinaion
Is jump
Is conditional
Evaluate

141
ESIL

CPU flags are usually defined as single bit registers in the RReg profile. They and sometimes found
under the 'flg' register type.

Variables
Properties of the VM variables:

1. They have no predefined bit width. This way it should be easy to extend them to 128, 256 and 512
bits later, e.g. for MMX, SSE, AVX, Neon SIMD.

2. There can be unbound number of variables. It is done for SSA-form compatibility.

3. Register names have no specific syntax. They are just strings.

4. Numbers can be specified in any base supported by RNum (dec, hex, oct, binary ...).

5. Each ESIL backend should have an associated RReg profile to describe the ESIL register specs.

Bit Arrays
What to do with them? What about bit arithmetics if use variables instead of registers?

Arithmetics
1. ADD ("+")
2. MUL ("*")
3. SUB ("-")
4. DIV ("/")
5. MOD ("%")

Bit Arithmetics
1. AND "&"
2. OR "|"
3. XOR "^"
4. SHL "<<"
5. SHR ">>"
6. ROL "<<<"
7. ROR ">>>"
8. NEG "!"

142
ESIL

6. ROL "<<<"
7. ROR ">>>"
8. NEG "!"

Floating Point Unit Support

At the moment of this writing, ESIL does not yet support FPU. But you can implement support for
unsupported instructions using r2pipe. Eventually we will get proper support for multimedia and
floating point.

Handling x86 REP Prefix in ESIL

ESIL specifies that the parsing control-flow commands must be uppercase. Bear in mind that some
architectures have uppercase register names. The corresponding register profile should take care not to
reuse any of the following:

3,SKIP - skip N instructions. used to make relative forward GOTOs

3,GOTO - goto instruction 3
LOOP - alias for 0,GOTO
BREAK - stop evaluating the expression
STACK - dump stack contents to screen
CLEAR - clear stack

Usage Example:
rep cmpsb

cx,!,?{,BREAK,},esi,[1],edi,[1],==,?{,BREAK,},esi,++,edi,++,cx,--,0,GOTO

Unimplemented/Unhandled Instructions
Those are expressed with the 'TODO' command. They act as a 'BREAK', but displays a warning
message describing that an instruction is not implemented and will not be emulated. For example:

fmulp ST(1), ST(0) => TODO,fmulp ST(1),ST(0)

ESIL Disassembly Example:

143
ESIL

[0x1000010f8]> e asm.esil=true
[0x1000010f8]> pd $r @ entry0
0x1000010f8 55 8,rsp,-=,rbp,rsp,=[8]
0x1000010f9 4889e5 rsp,rbp,=
0x1000010fc 4883c768 104,rdi,+=
0x100001100 4883c668 104,rsi,+=
0x100001104 5d rsp,[8],rbp,=,8,rsp,+=
0x100001105 e950350000 0x465a,rip,= ;[1]
0x10000110a 55 8,rsp,-=,rbp,rsp,=[8]
0x10000110b 4889e5 rsp,rbp,=
0x10000110e 488d4668 rsi,104,+,rax,=
0x100001112 488d7768 rdi,104,+,rsi,=
0x100001116 4889c7 rax,rdi,=
0x100001119 5d rsp,[8],rbp,=,8,rsp,+=
0x10000111a e93b350000 0x465a,rip,= ;[1]
0x10000111f 55 8,rsp,-=,rbp,rsp,=[8]
0x100001120 4889e5 rsp,rbp,=
0x100001123 488b4f60 rdi,96,+,[8],rcx,=
0x100001127 4c8b4130 rcx,48,+,[8],r8,=
0x10000112b 488b5660 rsi,96,+,[8],rdx,=
0x10000112f b801000000 1,eax,=
0x100001134 4c394230 rdx,48,+,[8],r8,==,cz,?=
0x100001138 7f1a sf,of,!,^,zf,!,&,?{,0x1154,rip,=,} ;[2]
0x10000113a 7d07 of,!,sf,^,?{,0x1143,rip,} ;[3]
0x10000113c b8ffffffff 0xffffffff,eax,= ; 0xffffffff
0x100001141 eb11 0x1154,rip,= ;[2]
0x100001143 488b4938 rcx,56,+,[8],rcx,=
0x100001147 48394a38 rdx,56,+,[8],rcx,==,cz,?=

Introspection
To ease ESIL parsing we should have a way to express introspection expressions to extract the data that
we want. For example, we may want to get the target address of a jump. The parser for ESIL
expressions should offer an API to make it possible to extract information by analyzing the expressions
easily.

> ao~esil,opcode
opcode: jmp 0x10000465a
esil: 0x10000465a,rip,=

We need a way to retrieve the numeric value of 'rip'. This is a very simple example, but there are more
complex, like conditional ones. We need expressions to be able to get:

opcode type
destination of a jump
144
ESIL

condition depends on
all regs modified (write)
all regs accessed (read)

API HOOKS
It is important for emulation to be able to setup hooks in the parser, so we can extend it to implement
analysis without having to change it again and again. That is, every time an operation is about to be
executed, a user hook is called. It can be used for example to determine if RIP is going to change, or if
the instruction updates the stack. Later, we can split that callback into several ones to have an event-
based analysis API that may be extended in JavaScript like this:

esil.on('regset', function(){..
esil.on('syscall', function(){esil.regset('rip'

For the API, see the functions hook_flag_read() , hook_execute() and hook_mem_read() . A
callback should return true or 1 if you want to override the action that it takes. For example, to deny
memory reads in a region, or voiding memory writes, effectively making it read-only. Return false or 0
if you want to trace ESIL expression parsing.

Other operations require bindings to external functionalities to work. In this case, r_ref and r_io .
This must be defined when initializing the ESIL VM.

Io Get/Set

Out ax, 44
44,ax,:ou

Selectors (cs,ds,gs...)

Mov eax, ds:[ebp+8]

Ebp,8,+,:ds,eax,=

145
Analysis

Data and Code Analysis

Radare2 has a very rich set of commands and configuration options to perform data and code analysis,
to extract useful information from a binary, like pointers, string references, basic blocks, opcode data,
jump targets, cross references and much more. These operations are handled by the a (analyze)
command family:

|Usage: a[abdefFghoprxstc] [...]

| aa[?] analyze all (fcns + bbs) (aa0 to avoid sub renaming)
| a8 [hexpairs] analyze bytes
| ab[b] [addr] analyze block at given address
| abb [len] analyze N basic blocks in [len] (section.size by default)
| abt [addr] find paths in the bb function graph from current offset to given ad
dress
| ac [cycles] analyze which op could be executed in [cycles]
| ad[?] analyze data trampoline (wip)
| ad [from] [to] analyze data pointers to (from-to)
| ae[?] [expr] analyze opcode eval expression (see ao)
| af[?] analyze Functions
| aF same as above, but using anal.depth=1
| ag[?] [options] draw graphs in various formats
| ah[?] analysis hints (force opcode size, ...)
| ai [addr] address information (show perms, stack, heap, ...)
| an [name] [@addr] show/rename/create whatever flag/function is used at addr
| ao[?] [len] analyze Opcodes (or emulate it)
| aO[?] [len] Analyze N instructions in M bytes
| ap find prelude for current offset
| ar[?] like 'dr' but for the esil vm. (registers)
| as[?] [num] analyze syscall using dbg.reg
| av[?] [.] show vtables
| ax[?] manage refs/xrefs (see also afx?)

In fact, a namespace is one of the biggest in radare2 tool and allows to control very different parts of
the analysis:

Code flow analysis

Data references analysis
Using loaded symbols
Managing different type of graphs, like CFG and call graph
Manage variables
Manage types
Emulation using ESIL VM
146
Analysis

Opcode introspection
Objects information, like virtual tables

147
Code Analysis

Code Analysis
Code analysis is a common technique used to extract information from assembly code.

Radare2 has different code analysis techniques implemented in the core and available in different
commands.

As long as the whole functionalities of r2 are available with the API as well as using commands. This
gives you the ability to implement your own analysis loops using any programming language, even with
r2 oneliners, shellscripts, or analysis or core native plugins.

The analysis will show up the internal data structures to identify basic blocks, function trees and to
extract opcode-level information.

The most common radare2 analysis command sequence is aa , which stands for "analyze all". That all
is referring to all symbols and entry-points. If your binary is stripped you will need to use other
commands like aaa , aab , aar , aac or so.

Take some time to understand what each command does and the results after running them to find the
best one for your needs.

148
Code Analysis

| 0x0804868a 85c0 test eax, eax

| ,=< 0x0804868c 7911 jns 0x804869f
| | 0x0804868e c70424cf870. mov dword [esp], str.Don_tuseadebuguer_ ; 0x080487cf
| | 0x08048695 e882fdffff call sym..imp.puts
| | sym..imp.puts()
| | 0x0804869a e80dfdffff call sym..imp.abort
| | sym..imp.abort()
| `-> 0x0804869f 83fb02 cmp ebx, 0x2
|,==< 0x080486a2 7411 je 0x80486b5
|| 0x080486a4 c704240c880. mov dword [esp], str.Youmustgiveapasswordforusethisprog
ram_ ; 0x0804880c
|| 0x080486ab e86cfdffff call sym..imp.puts
|| sym..imp.puts()
|| 0x080486b0 e8f7fcffff call sym..imp.abort
|| sym..imp.abort()
|`--> 0x080486b5 8b4604 mov eax, [esi+0x4]
| 0x080486b8 890424 mov [esp], eax
| 0x080486bb e8e5feffff call fcn.080485a5
| fcn.080485a5() ; fcn.080484c6+223
| 0x080486c0 b800000000 mov eax, 0x0
| 0x080486c5 8b4df4 mov ecx, [ebp-0xc]
| 0x080486c8 8b5df8 mov ebx, [ebp-0x8]
| 0x080486cb 8b75fc mov esi, [ebp-0x4]
| 0x080486ce 89ec mov esp, ebp
| 0x080486d0 5d pop ebp
| 0x080486d1 8d61fc lea esp, [ecx-0x4]
\ 0x080486d4 c3 ret

In this example, we analyze the whole file ( aa ) and then print disassembly of the main() function
( pdf ). The aa command belongs to the family of auto analysis commands and performs only the
most basic auto analysis steps. In radare2 there are many different types of the auto analysis commands
with a different analysis depth, including partial emulation: aa , aaa , aab , aaaa , ... There is also a
mapping of those commands to the r2 CLI options: r2 -A , r2 -AA , and so on.

It is a common sense that completely automated analysis can produce non sequitur results, thus radare2
provides separate commands for the particular stages of the analysis allowing fine-grained control of the
analysis process. Moreover, there is a treasure trove of configuration variables for controlling the
analysis outcomes. You can find them in anal.* and emu.* cfg variables' namespaces.

One of the most important "basic" analysis commands is the set of af subcommands. af means
"analyze function". Using this command you can either allow automatic analysis of the particular
function or perform completely manual one.

149
Code Analysis

[0x00000000]> af?
|Usage: af
| af ([name]) ([addr]) analyze functions (start at addr or $$)
| afr ([name]) ([addr]) analyze functions recursively
| af+ addr name [type] [diff] hand craft a function (requires afb+)
| af- [addr] clean all function analysis data (or function at addr)
| afb+ fcnA bbA sz [j] [f] ([t]( [d])) add bb to function @ fcnaddr
| afb[?] [addr] List basic blocks of given function
| afB 16 set current function as thumb (change asm.bits)
| afC[lc] ([addr])@[addr] calculate the Cycles (afC) or Cyclomatic Complexity (afCc)
| afc[?] type @[addr] set calling convention for function
| afd[addr] show function + delta for given offset
| aff re-adjust function boundaries to fit
| afF[1|0|] fold/unfold/toggle
| afi [addr|fcn.name] show function(s) information (verbose afl)
| afl[?] [l*] [fcn name] list functions (addr, size, bbs, name) (see afll)
| afm name merge two functions
| afM name print functions map
| afn[?] name [addr] rename name for function at address (change flag too)
| afna suggest automatic name for current offset
| afo [fcn.name] show address for the function named like this
| afs [addr] [fcnsign] get/set function signature at current address
| afS[stack_size] set stack frame size for function at current address
| aft[?] type matching, type propagation
| afu [addr] resize and analyze function from current address until addr
| afv[bsra]? manipulate args, registers and variables in function
| afx list function references

Some of the most challenging tasks while performing a function analysis are merge, crop and resize. As
with other analysis commands you have two modes: semi-automatic and manual. For the semi-
automatic, you can use afm <function name> to merge the current function with the one specified by
name as an argument, aff to readjust the function after analysis changes or function edits, afu
<address> to do the resize and analysis of the current function until the specified address.

Apart from those semi-automatic ways to edit/analyze the function, you can hand craft it in the manual
mode with af+ command and edit basic blocks of it using afb commands. Before changing the
basic blocks of the function it is recommended to check the already presented ones:

[0x00003ac0]> afb
0x00003ac0 0x00003b7f 01:001A 191 f 0x00003b7f
0x00003b7f 0x00003b84 00:0000 5 j 0x00003b92 f 0x00003b84
0x00003b84 0x00003b8d 00:0000 9 f 0x00003b8d
0x00003b8d 0x00003b92 00:0000 5
0x00003b92 0x00003ba8 01:0030 22 j 0x00003ba8
0x00003ba8 0x00003bf9 00:0000 81

150
Code Analysis

There are two very important commands for this: afc and afB . The latter is a must-know command
for some platforms like ARM. It provides a way to change the "bitness" of the particular function.
Basically, allowing to select between ARM and Thumb modes.

afc on the other side, allows to manually specify function calling convention. You can find more

information on its usage in calling_conventions.

Recursive analysis
There are 4 important program wide half-automated analysis commands:

aab - perform basic-block analysis ("Nucleus" algorithm)

aac - analyze function calls from one (selected or current function)

aaf - analyze all function calls

aar - analyze data references

aad - analyze pointers to pointers references

Those are only generic semi-automated reference searching algorithms. Radare2 provides a wide choice
of manual references' creation of any kind. For this fine-grained control you can use ax commands.

|Usage: ax[?d-l*] # see also 'afx?'

The most commonly used ax commands are axt and axf , especially as a part of various r2pipe
scripts. Lets say we see the string in the data or a code section and want to find all places it was
referenced from, we should use axt :

151
Code Analysis

[0x0001783a]> pd 2
;-- str.02x:
; STRING XREF from 0x00005de0 (sub.strlen_d50)
; CODE XREF from 0x00017838 (str.._s_s_s + 7)
0x0001783a .string "%%%02x" ; len=7
;-- str.src_ls.c:
; STRING XREF from 0x0000541b (sub.free_b04)
; STRING XREF from 0x0000543a (sub.__assert_fail_41f + 27)
; STRING XREF from 0x00005459 (sub.__assert_fail_41f + 58)
; STRING XREF from 0x00005f9e (sub._setjmp_e30)
; CODE XREF from 0x0001783f (str.02x + 5)
0x00017841 .string "src/ls.c" ; len=9
[0x0001783a]> axt
sub.strlen_d50 0x5de0 [STRING] lea rcx, str.02x
(nofunc) 0x17838 [CODE] jae str.02x

Apart from predefined algorithms to identify functions there is a way to specify a function prelude with
a configuration option anal.prelude . For example, like e anal.prelude = 0x554889e5 which means

push rbp
mov rbp, rsp

on x86_64 platform. It should be specified before any analysis commands.

Configuration
Radare2 allows to change the behavior of almost any analysis stages or commands. There are different
kinds of the configuration options:

Flow control
Basic blocks control
References control
IO/Ranges
Jump tables analysis control
Platform/target specific options

Control flow configuration

Two most commonly used options for changing the behavior of control flow analysis in radare2 are
anal.hasnext and anal.afterjump . The first one allows forcing radare2 to continue the analysis

after the end of the function, even if the next chunk of the code wasn't called anywhere, thus analyzing
152
Code Analysis

all of the available functions. The latter one allows forcing radare2 to continue the analysis even after
unconditional jumps.

In addition to those we can also set anal.ijmp to follow the indirect jumps, continuing analysis;
anal.pushret to analyze push ...; ret sequence as a jump; anal.nopskip to skip the NOP

sequences at a function beginning.

For now, radare2 also allows you to change the maximum basic block size with anal.bb.maxsize
option . The default value just works in most use cases, but it's useful to increase that for example when
dealing with obfuscated code. Beware that some of basic blocks control options may disappear in the
future in favor of more automated ways to set those.

For some unusual binaries or targets, there is an option anal.noncode . Radare2 doesn't try to analyze
data sections as a code by default. But in some cases - malware, packed binaries, binaries for embedded
systems, it is often a case. Thus - this option.

Reference control
The most crucial options that change the analysis results drastically. Sometimes some can be disabled to
save the time and memory when analyzing big binaries.

anal.jmpref - to allow references creation for unconditional jumps

anal.cjmpref - same, but for conditional jumps

anal.datarefs - to follow the data references in code

anal.refstr - search for strings in data references

anal.strings - search for strings and creating references

Note that strings references control is disabled by default because it increases the analysis time.

Analysis ranges
There are a few options for this:

anal.limits - enables the range limits for analysis operations

anal.from - starting address of the limit range

anal.to - the corresponding end of the limit range

anal.in - specify search boundaries for analysis ( io.maps , io.sections.exec , dbg.maps

and many more - see e anal.in=? for the complete list)

Jump tables
153
Code Analysis

Jump tables are one of the trickiest targets in binary reverse engineering. There are hundreds of different
types, the end result depending on the compiler/linker and LTO stages of optimization. Thus radare2
allows enabling some experimental jump tables detection algorithms using anal.jmptbl option.
Eventually, algorithms moved into the default analysis loops once they start to work on every supported
platform/target/testcase. Two more options can affect the jump tables analysis results too:

anal.ijmp - follow the indirect jumps, some jump tables rely on them

anal.datarefs - follow the data references, some jump tables use those

Platform specific controls

There are two common problems when analyzing embedded targets: ARM/Thumb detection and MIPS
GP value. In case of ARM binaries radare2 supports some auto-detection of ARM/Thumb mode
switches, but beware that it uses partial ESIL emulation, thus slowing the analysis process. If you will
not like the results, particular functions' mode can be overridden with afB command.

The MIPS GP problem is even trickier. It is a basic knowledge that GP value can be different not only
for the whole program, but also for some functions. To partially solve that there are options anal.gp
and anal.gp2 . The first one sets the GP value for the whole program or particular function. The latter
allows to "constantify" the GP value if some code is willing to change its value, always resetting it if the
case. Those are heavily experimental and might be changed in the future in favor of more automated
analysis.

Visuals
One of the easiest way to see and check the changes of the analysis commands and variables is to
perform a scrolling in a Vv special visual mode, allowing functions preview:

When we want to check how analysis changes affect the result in the case of big functions, we can use
minimap instead, allowing to see a bigger flow graph on the same screen size. To get into the minimap
mode type VV then press p twice:
154
Code Analysis

This mode allows you to see the disassembly of each node separately, just navigate between them using
Tab key.

Analysis hints
It is not an uncommon case that analysis results are not perfect even after you tried every single
configuration option. This is where the "analysis hints" radare2 mechanism comes in. It allows to
override some basic opcode or meta-information properties, or even to rewrite the whole opcode string.
These commands are located under ah namespace:

155
Code Analysis

|Usage: ah[lba-]Analysis Hints

One of the most common cases is to set a particular numeric base for immediates:

[0x00003d54]> ahi?
|Usage ahi [sbodh] [@ offset] Define numeric base
| ahi [base] set numeric base (1, 2, 8, 10, 16)
| ahi b set base to binary (2)
| ahi d set base to decimal (10)
| ahi h set base to hexadecimal (16)
| ahi o set base to octal (8)
| ahi p set base to htons(port) (3)
| ahi i set base to IP address (32)
| ahi S set base to syscall (80)
| ahi s set base to string (1)
[0x00003d54]> pd 2
0x00003d54 0583000000 add eax, 0x83
0x00003d59 3d13010000 cmp eax, 0x113
[0x00003d54]> ahi d
[0x00003d54]> pd 2
0x00003d54 0583000000 add eax, 131
0x00003d59 3d13010000 cmp eax, 0x113
[0x00003d54]> ahi b
[0x00003d54]> pd 2
0x00003d54 0583000000 add eax, 10000011b
0x00003d59 3d13010000 cmp eax, 0x113

156
Code Analysis

It is notable that some analysis stages or commands add the internal analysis hints, which can be
checked with ah command:

[0x00003d54]> ah
0x00003d54 - 0x00003d54 => immbase=2
[0x00003d54]> ah*
ahi 2 @ 0x3d54

Sometimes we need to override jump or call address, for example in case of tricky relocation, which is
unknown for radare2, thus we can change the value manually. The current analysis information about a
particular opcode can be checked with ao command. We can use ahc command for performing such
a change:

157
Code Analysis

[0x00003cee]> pd 2
0x00003cee e83d080100 call sub.__errno_location_530
0x00003cf3 85c0 test eax, eax
[0x00003cee]> ao
address: 0x3cee
opcode: call 0x14530
mnemonic: call
prefix: 0
id: 56
bytes: e83d080100
refptr: 0
size: 5
sign: false
type: call
cycles: 3
esil: 83248,rip,8,rsp,-=,rsp,=[],rip,=
jump: 0x00014530
direction: exec
fail: 0x00003cf3
stack: null
family: cpu
stackop: null
[0x00003cee]> ahc 0x5382
[0x00003cee]> pd 2
0x00003cee e83d080100 call sub.__errno_location_530
0x00003cf3 85c0 test eax, eax
[0x00003cee]> ao
address: 0x3cee
opcode: call 0x14530
mnemonic: call
prefix: 0
id: 56
bytes: e83d080100
refptr: 0
size: 5
sign: false
type: call
cycles: 3
esil: 83248,rip,8,rsp,-=,rsp,=[],rip,=
jump: 0x00005382
direction: exec
fail: 0x00003cf3
stack: null
family: cpu
stackop: null
[0x00003cee]> ah
0x00003cee - 0x00003cee => jump: 0x5382

158
Code Analysis

As you can see, despite the unchanged disassembly view the jump address in opcode was changed
( jump option).

If anything of the previously described didn't help, you can simply override shown disassembly with
anything you like:

[0x00003d54]> pd 2
0x00003d54 0583000000 add eax, 10000011b
0x00003d59 3d13010000 cmp eax, 0x113
[0x00003d54]> "aho myopcode bla, foo"
[0x00003d54]> pd 2
0x00003d54 myopcode bla, foo
0x00003d55 830000 add dword [rax], 0

159
Variables

Managing variables
Radare2 allows managing local variables, no matter their location, stack or registers. The variables' auto
analysis is enabled by default but can be disabled with anal.vars configuration option.

The main variables commands are located in afv namespace:

|Usage: afv[rbs]
| afvr[?] manipulate register based arguments
| afvb[?] manipulate bp based arguments/locals
| afvs[?] manipulate sp based arguments/locals
| afv* output r2 command to add args/locals to flagspace
| afvR [varname] list addresses where vars are accessed (READ)
| afvW [varname] list addresses where vars are accessed (WRITE)
| afva analyze function arguments/locals
| afvd name output r2 command for displaying the value of args/locals
in the
debugger
| afvn [old_name] [new_name] rename argument/local
| afvt [name] [new_type] change type for given argument/local
| afv-([name]) remove all or given var

afvr , afvb and afvs commands are uniform but allow manipulation of register-based arguments

and variables, BP/FP-based arguments and variables, and SP-based arguments and variables
respectively. If we check the help for afvr we will get the way two others commands works too:

|Usage: afvr [reg] [type] [name]

| afvr list register based arguments
| afvr* same as afvr but in r2 commands
| afvr [reg] [name] ([type]) define register arguments
| afvrj return list of register arguments in JSON format
| afvr- [name] delete register arguments at the given index
| afvrg [reg] [addr] define argument get reference
| afvrs [reg] [addr] define argument set reference

Like many other things variables detection is performed by radare2 automatically, but results can be
changed with those arguments/variables control commands. This kind of analysis relies heavily on
preloaded function prototypes and the calling-convention, thus loading symbols can improve it.
Moreover, after changing something we can rerun variables analysis with afva command. Quite often
variables analysis is accompanied with types analysis, see afta command.

160
Variables

The most important aspect of reverse engineering - naming things. Of course, you can rename variable
too, affecting all places it was referenced. This can be achieved with afvn for any type of argument or
variable. Or you can simply remove the variable or argument with afv- command.

As mentioned before the analysis loop relies heavily on types information while performing variables
analysis stages. Thus comes next very important command - afvt , which allows you to change the
type of variable:

[0x00003b92]> afvs
var int local_8h @ rsp+0x8
var int local_10h @ rsp+0x10
var int local_28h @ rsp+0x28
var int local_30h @ rsp+0x30
var int local_32h @ rsp+0x32
var int local_38h @ rsp+0x38
var int local_45h @ rsp+0x45
var int local_46h @ rsp+0x46
var int local_47h @ rsp+0x47
var int local_48h @ rsp+0x48
[0x00003b92]> afvt local_10h char*
[0x00003b92]> afvs
var int local_8h @ rsp+0x8
var char* local_10h @ rsp+0x10
var int local_28h @ rsp+0x28
var int local_30h @ rsp+0x30
var int local_32h @ rsp+0x32
var int local_38h @ rsp+0x38
var int local_45h @ rsp+0x45
var int local_46h @ rsp+0x46
var int local_47h @ rsp+0x47
var int local_48h @ rsp+0x48

Less commonly used feature, which is still under heavy development - distinction between variables
being read and written. You can list those being read with afvR command and those being written
with afvW command. Both commands provide a list of the places those operations are performed:

161
Variables

[0x00003b92]> afvR
local_48h 0x48ee
local_30h 0x3c93,0x520b,0x52ea,0x532c,0x5400,0x3cfb
local_10h 0x4b53,0x5225,0x53bd,0x50cc
local_8h 0x4d40,0x4d99,0x5221,0x53b9,0x50c8,0x4620
local_28h 0x503a,0x51d8,0x51fa,0x52d3,0x531b
local_38h
local_45h 0x50a1
local_47h
local_46h
local_32h 0x3cb1
[0x00003b92]> afvW
local_48h 0x3adf
local_30h 0x3d3e,0x4868,0x5030
local_10h 0x3d0e,0x5035
local_8h 0x3d13,0x4d39,0x5025
local_28h 0x4d00,0x52dc,0x53af,0x5060,0x507a,0x508b
local_38h 0x486d
local_45h 0x5014,0x5068
local_47h 0x501b
local_46h 0x5083
local_32h
[0x00003b92]>

Type inference
The type inference for local variables and arguments is well integrated with the command afta .

Let's see an example of this with a simple hello_world binary

162
Variables

After applying afta

163
Variables

It also extracts type information from format strings like printf ("fmt : %s , %u , %d", ...) , the
format specifications are extracted from anal/d/spec.sdb

You could create a new profile for specifying a set of format chars depending on different
libraries/operating systems/programming languages like this :

win=spec
spec.win.u32=unsigned int

Then change your default specification to newly created one using this config variable e anal.spec =
win

For more information about primitive and user-defined types support in radare2 refer to types chapter.

164
Types

Types
Radare2 supports the C-syntax data types description. Those types are parsed by a C11-compatible
parser and stored in the internal SDB, thus are introspectable with k command.

Most of the related commands are located in t namespace:

Note that the basic (atomic) types are not those from C standard - not char , _Bool , or short .
Because those types can be different from one platform to another, radare2 uses definite types like as
int8_t or uint64_t and will convert int to int32_t or int64_t depending on the binary or

debuggee platform/compiler.

Basic types can be listed using t command, for the structured types you need to use ts , tu or te
for enums:

165
Types

[0x000051c0]> t
char
char *
int
int16_t
int32_t
int64_t
int8_t
long
long long
...

Loading types
There are three easy ways to define a new type:

Directly from the string using td command

From the file using to <filename> command
Open an $EDITOR to type the definitions in place using to -

[0x000051c0]> "td struct foo {char* a; int b;}"

[0x000051c0]> cat ~/radare2-regressions/bins/headers/s3.h
struct S1 {
int x[3];
int y[4];
int z;
};
[0x000051c0]> to ~/radare2-regressions/bins/headers/s3.h
[0x000051c0]> ts
foo
S1

Also note there is a config option to specify include directories for types parsing

[0x00000000]> e??~dir.type
dir.types: Default path to look for cparse type files
[0x00000000]> e dir.types
/usr/include

Printing types
Notice below we have used ts command, which basically converts the C type description (or to be
precise it's SDB representation) into the sequence of pf commands. See more about print format.

166
Types

The tp command uses the pf string to print all the members of type at the current offset/given
address:

[0x000051c0]> ts foo
pf zd a b
[0x000051c0]> tp foo
a : 0x000051c0 = 'hello'
b : 0x000051cc = 10
[0x000051c0]> tp foo 0x000053c0
a : 0x000053c0 = 'world'
b : 0x000053cc = 20

Also, you could fill your own data into the struct and print it using tpx command

[0x000051c0]> tpx foo 4141414144141414141442001000000

a : 0x000051c0 = AAAAD.....B
b : 0x000051cc = 16

Linking Types
The tp command just performs a temporary cast. But if we want to link some address or variable with
the chosen type, we can use tl command to store the relationship in SDB.

[0x000051c0]> tl S1 = 0x51cf
[0x000051c0]> tl
(S1)
x : 0x000051cf = [ 2315619660, 1207959810, 34803085 ]
y : 0x000051db = [ 2370306049, 4293315645, 3860201471, 4093649307 ]
z : 0x000051eb = 4464399

Moreover, the link will be shown in the disassembly output or visual mode:

167
Types

[0x000051c0 15% 300 /bin/ls]> pd $r @ entry0

;-- entry0:
0x000051c0 xor ebp, ebp
0x000051c2 mov r9, rdx
0x000051c5 pop rsi
0x000051c6 mov rdx, rsp
0x000051c9 and rsp, 0xfffffffffffffff0
0x000051cd push rax
0x000051ce push rsp
(S1)
x : 0x000051cf = [ 2315619660, 1207959810, 34803085 ]
y : 0x000051db = [ 2370306049, 4293315645, 3860201471, 4093649307 ]
z : 0x000051eb = 4464399
0x000051f0 lea rdi, loc._edata ; 0x21f248
0x000051f7 push rbp
0x000051f8 lea rax, loc._edata ; 0x21f248
0x000051ff cmp rax, rdi
0x00005202 mov rbp, rsp

Once the struct is linked, radare2 tries to propagate structure offset in the function at current offset, to
run this analysis on whole program or at any targeted functions after all structs are linked you have
taa command:

[0x00000000]> ta?
| taa [fcn] Analyze all/given function to convert immediate to linked structur
e offsets (see tl?)

Note sometimes the emulation may not be accurate, for example as below :

|0x000006da push rbp

The return value of malloc may differ between two emulations, so you have to set the hint for return
value manually using ahr command, so run tl or taa command after setting up the return value
hint.

[0x000006da]> ah?
| ahr val set hint for return value of a function

168
Types

Structure Immediates
There is one more important aspect of using types in radare2 - using ta you can change the immediate
in the opcode to the structure offset. Lets see a simple example of [R]SI-relative addressing

[0x000052f0]> pd 1
0x000052f0 mov rax, qword [rsi + 8] ; [0x8:8]=0

Here 8 - is some offset in the memory, where rsi probably holds some structure pointer. Imagine
that we have the following structures

[0x000052f0]> "td struct ms { char b[8]; int member1; int member2; };"
[0x000052f0]> "td struct ms1 { uint64_t a; int member1; };"
[0x000052f0]> "td struct ms2 { uint16_t a; int64_t b; int member1; };"

Now we need to set the proper structure member offset instead of 8 in this instruction. At first, we
need to list available types matching this offset:

[0x000052f0]> tas 8
ms.member1
ms1.member1

Note, that ms2 is not listed, because it has no members with offset 8 . After listing available options
we can link it to the chosen offset at the current address:

[0x000052f0]> ta ms1.member1
[0x000052f0]> pd 1
0x000052f0 488b4608 mov rax, qword [rsi + ms1.member1] ; [0x8:8]=0

Managing enums
Printing all fields in enum using te command

[0x00000000]> "td enum Foo {COW=1,BAR=2};"

[0x00000000]> te Foo
COW = 0x1
BAR = 0x2

Finding matching enum member for given bitfield and vice-versa

169
Types

[0x00000000]> te Foo 0x1

COW
[0x00000000]> teb Foo COW
0x1

Internal representation
To see the internal representation of the types you can use tk command:

[0x000051c0]> tk~S1
S1=struct
struct.S1=x,y,z
struct.S1.x=int32_t,0,3
struct.S1.x.meta=4
struct.S1.y=int32_t,12,4
struct.S1.y.meta=4
struct.S1.z=int32_t,28,0
struct.S1.z.meta=0
[0x000051c0]>

Defining primitive types requires an understanding of basic pf formats, you can find the whole list of
format specifier in pf?? :

170
Types

-----------------------------------------------------
| format | explanation |
|---------------------------------------------------|
| b | byte (unsigned) |
| c | char (signed byte) |
| d | 0x%%08x hexadecimal value (4 bytes) |
| f | float value (4 bytes) |
| i | %%i integer value (4 bytes) |
| o | 0x%%08o octal value (4 byte) |
| p | pointer reference (2, 4 or 8 bytes) |
| q | quadword (8 bytes) |
| s | 32bit pointer to string (4 bytes) |
| S | 64bit pointer to string (8 bytes) |
| t | UNIX timestamp (4 bytes) |
| T | show Ten first bytes of buffer |
| u | uleb128 (variable length) |
| w | word (2 bytes unsigned short in hex) |
| x | 0x%%08x hex value and flag (fd @ addr) |
| X | show formatted hexpairs |
| z | \0 terminated string |
| Z | \0 terminated wide string |
-----------------------------------------------------

there are basically 3 mandatory keys for defining basic data types: X=type

type.X=format_specifier type.X.size=size_in_bits For example, let's define UNIT , according to

Microsoft documentation.aspx#UINT ) UINT is just equivalent of standard C unsigned int (or

uint32_t in terms of TCC engine). It will be defined as:

UINT=type
type.UINT=d
type.UINT.size=32

Now there is an optional entry:

X.type.pointto=Y

This one may only be used in case of pointer type.X=p , one good example is LPFILETIME definition,
it is a pointer to _FILETIME which happens to be a structure. Assuming that we are targeting only 32-
bit windows machine, it will be defined as the following:

LPFILETIME=type
type.LPFILETIME=p
type.LPFILETIME.size=32
type.LPFILETIME.pointto=_FILETIME

171
Types

This last field is not mandatory because sometimes the data structure internals will be proprietary, and
we will not have a clean representation for it.

There is also one more optional entry:

type.UINT.meta=4

This entry is for integration with C parser and carries the type class information: integer size,
signed/unsigned, etc.

Structures
Those are the basic keys for structs (with just two elements):

X=struct
struct.X=a,b
struct.X.a=a_type,a_offset,a_number_of_elements
struct.X.b=b_type,b_offset,b_number_of_elements

The first line is used to define a structure called X , the second line defines the elements of X as
comma separated values. After that, we just define each element info.

For example. we can have a struct like this one:

struct _FILETIME {
DWORD dwLowDateTime;
DWORD dwHighDateTime;
}

assuming we have DWORD defined, the struct will look like this

_FILETIME=struct
struct._FILETIME=dwLowDateTime,dwHighDateTime
struct._FILETIME.dwLowDateTime=DWORD,0,0
struct._FILETIME.dwHighDateTime=DWORD,4,0

Note that the number of elements filed is used in case of arrays only to identify how many elements are
in arrays, other than that it is zero by default.

Unions
172
Types

Unions are defined exactly like structs the only difference is that you will replace the word struct
with the word union .

Function prototypes
Function prototypes representation is the most detail oriented and the most important one of them all.
Actually, this is the one used directly for type matching

X=func
func.X.args=NumberOfArgs
func.x.arg0=Arg_type,arg_name
.
.
.
func.X.ret=Return_type
func.X.cc=calling_convention

It should be self-explanatory. Let's do strncasecmp as an example for x86 arch for Linux machines.
According to man pages, strncasecmp is defined as the following:

int strcasecmp(const char s1, const char s2, size_t n);

When converting it into its sdb representation it will look like the following:

strcasecmp=func
func.strcasecmp.args=3
func.strcasecmp.arg0=char *,s1
func.strcasecmp.arg1=char *,s2
func.strcasecmp.arg2=size_t,n
func.strcasecmp.ret=int
func.strcasecmp.cc=cdecl

Note that the .cc part is optional and if it didn't exist the default calling-convention for your target
architecture will be used instead. There is one extra optional key

func.x.noreturn=true/false

This key is used to mark functions that will not return once called, such as exit and _exit .

173
Types

174
Calling Conventions

Calling Conventions
Radare2 uses calling conventions to help in identifying function formal arguments and return types. It is
used also as a guide for basic function prototype and type propagation.

[0x00000000]> afc?
|Usage: afc[agl?]
| afc convention Manually set calling convention for current function
| afc Show Calling convention for the Current function
| afcr[j] Show register usage for the current function
| afca Analyse function for finding the current calling convention
| afcf name Prints return type function(arg1, arg2...)
| afcl List all available calling conventions
| afco path Open Calling Convention sdb profile from given path
[0x00000000]>

To list all available calling conventions for current architecture using afcl command

[0x00000000]> afcl
amd64
ms

To display function prototype of standard library functions you have afcf command

[0x00000000]> afcf printf

int printf(const char *format)
[0x00000000]> afcf fgets
char *fgets(char *s, int size, FILE *stream)

All this information is loaded via sdb under /libr/anal/d/cc-[arch]-[bits].sdb

default.cc=amd64

ms=cc
cc.ms.name=ms
cc.ms.arg1=rcx
cc.ms.arg2=rdx
cc.ms.arg3=r8
cc.ms.arg3=r9
cc.ms.argn=stack
cc.ms.ret=rax

175
Calling Conventions

cc.x.argi=rax is used to set the ith argument of this calling convention to register name rax

cc.x.argn=stack means that all the arguments (or the rest of them in case there was argi for any i as

counting number) will be stored in stack from left to right

cc.x.argn=stack_rev same as cc.x.argn=stack except for it means argument are passed right to left

176
Virtual Tables

Virtual Tables
There is a basic support of virtual tables parsing (RTTI and others). The most important thing before
you start to perform such kind of analysis is to check if the anal.cpp.abi option is set correctly, and
change if needed.

All commands to work with virtual tables are located in the av namespace. Currently, the support is
very basic, allowing you only to inspect parsed tables.

|Usage: av[?jr*] C++ vtables and RTTI

| av search for vtables in data sections and show results
| avj like av, but as json
| av* like av, but as r2 commands
| avr[j@addr] try to parse RTTI at vtable addr (see anal.cpp.abi)
| avra[j] search for vtables and try to parse RTTI at each of them

The main commands here are av and avr . av lists all virtual tables found when r2 opened the file.
If you are not happy with the result you may want to try to parse virtual table at a particular address
with avr command. avra performs the search and parsing of all virtual tables in the binary, like r2
does during the file opening.

177
Syscalls

Syscalls
Radare2 allows manual search for assembly code looking like a syscall operation. For example on ARM
platform usually they are represented by the svc instruction, on the others can be a different
instructions, e.g. syscall on x86 PC.

[0x0001ece0]> /c svc
...
0x000187c2 # 2: svc 0x76
0x000189ea # 2: svc 0xa9
0x00018a0e # 2: svc 0x82
...

Syscalls detection is driven by asm.os , asm.bits , and asm.arch . Be sure to setup those
configuration options accordingly. You can use asl command to check if syscalls' support is set up
properly and as you expect. The command lists syscalls supported for your platform.

[0x0001ece0]> asl
...
sd_softdevice_enable = 0x80.16
sd_softdevice_disable = 0x80.17
sd_softdevice_is_enabled = 0x80.18
...

If you setup ESIL stack with aei or aeim , you can use /as command to search the addresses
where particular syscalls were found and list them.

[0x0001ece0]> aei
[0x0001ece0]> /as
0x000187c2 sd_ble_gap_disconnect
0x000189ea sd_ble_gatts_sys_attr_set
0x00018a0e sd_ble_gap_sec_info_reply
...

To reduce searching time it is possible to restrict the searching range for only executable segments or
sections with /as @e:search.in=io.maps.x

Using the ESIL emulation radare2 can print syscall arguments in the disassembly output. To enable the
linear (but very rough) emulation use asm.emu configuration variable:

178
Syscalls

[0x0001ece0]> e asm.emu=true
[0x0001ece0]> s 0x000187c2
[0x000187c2]> pdf~svc
0x000187c2 svc 0x76 ; 118 = sd_ble_gap_disconnect
[0x000187c2]>

In case of executing aae (or aaaa which calls aae ) command radare2 will push found syscalls to a
special syscall. flagspace, which can be useful for automation purpose:

[0x000187c2]> fs
0 0 * imports
1 0 * symbols
2 1523 * functions
3 420 * strings
4 183 * syscalls
[0x000187c2]> f~syscall
...
0x000187c2 1 syscall.sd_ble_gap_disconnect.0
0x000189ea 1 syscall.sd_ble_gatts_sys_attr_set
0x00018a0e 1 syscall.sd_ble_gap_sec_info_reply
...

It also can be interactively navigated through within HUD mode ( V_ )

0> syscall.sd_ble_gap_disconnect
- 0x000187b2 syscall.sd_ble_gap_disconnect
0x000187c2 syscall.sd_ble_gap_disconnect.0
0x00018a16 syscall.sd_ble_gap_disconnect.1
0x00018b32 syscall.sd_ble_gap_disconnect.2
0x0002ac36 syscall.sd_ble_gap_disconnect.3

179
Emulation

Emulation
One of the most important things to remember in reverse engineering is a core difference between static
analysis and dynamic analysis. As many already know, static analysis suffers from the path explosion
problem, which is impossible to solve even in the most basic way without at least a partial emulation.

Thus many professional reverse engineering tools use code emulation while performing an analysis of
binary code, and radare2 is no difference here.

For partial emulation (or imprecise full emulation) radare2 uses its own ESIL intermediate language and
virtual machine.

Radare2 supports this kind of partial emulation for all platforms that implement ESIL uplifting
(x86/x86_64, ARM, arm64, MIPS, powerpc, sparc, AVR, 8051, Gameboy, ...).

One of the most common usages of such emulation is to calculate indirect jumps and conditional jumps.

To see the ESIL representation of the program one can use the ao command or enable the asm.esil
configuration variable, to check if the program uplifted correctly, and to grasp how ESIL works:

180
Emulation

[0x00001660]> pdf
. (fcn) fcn.00001660 40
│ fcn.00001660 ();
│ ; CALL XREF from 0x00001713 (entry2.fini)
│ 0x00001660 lea rdi, obj.__progname ; 0x207220
│ 0x00001667 push rbp
│ 0x00001668 lea rax, obj.__progname ; 0x207220
│ 0x0000166f cmp rax, rdi
│ 0x00001672 mov rbp, rsp
│ .─< 0x00001675 je 0x1690
│ │ 0x00001677 mov rax, qword [reloc._ITM_deregisterTMCloneTable] ; [0x206fd8:8]=0
│ │ 0x0000167e test rax, rax
│.──< 0x00001681 je 0x1690
│││ 0x00001683 pop rbp
│││ 0x00001684 jmp rax
│``─> 0x00001690 pop rbp
` 0x00001691 ret
[0x00001660]> e asm.esil=true
[0x00001660]> pdf
. (fcn) fcn.00001660 40
│ fcn.00001660 ();
│ ; CALL XREF from 0x00001713 (entry2.fini)
│ 0x00001660 0x205bb9,rip,+,rdi,=
│ 0x00001667 rbp,8,rsp,-=,rsp,=[8]
│ 0x00001668 0x205bb1,rip,+,rax,=
│ 0x0000166f rdi,rax,==,$z,zf,=,$b64,cf,=,$p,pf,=,$s,sf,=,$o,of,=
│ 0x00001672 rsp,rbp,=
│ .─< 0x00001675 zf,?{,5776,rip,=,}
│ │ 0x00001677 0x20595a,rip,+,[8],rax,=
│ │ 0x0000167e 0,rax,rax,&,==,$z,zf,=,$p,pf,=,$s,sf,=,$0,cf,=,$0,of,=
│.──< 0x00001681 zf,?{,5776,rip,=,}
│││ 0x00001683 rsp,[8],rbp,=,8,rsp,+=
│││ 0x00001684 rax,rip,=
│``─> 0x00001690 rsp,[8],rbp,=,8,rsp,+=
` 0x00001691 rsp,[8],rip,=,8,rsp,+=

To manually setup the ESIL imprecise emulation you need to run this command sequence:

aei to initialize ESIL VM

aeim to initialize ESIL VM memory (stack)

aeip to set the initial ESIL VM IP (instruction pointer)

a sequence of aer commands to set the initial register values.

While performing emulation, please remember, that ESIL VM cannot emulate external calls or system
calls, along with SIMD instructions. Thus the most common scenario is to emulate only a small chunk
of the code, like encryption/decryption, unpacking or calculating something.

181
Emulation

After we successfully set up the ESIL VM we can interact with it like with a usual debugging mode.
Commands interface for ESIL VM is almost identical to the debugging one:

aes to step (or s key in visual mode)

aesi to step over the function calls

aesu <address> to step until some specified address

aesue <ESIL expression> to step until some specified ESIL expression met

aec to continue until break (Ctrl-C), this one is rarely used though, due to the omnipresence of

external calls
aecu <address> to continue until some specified address

In visual mode, all of the debugging hotkeys will work also in ESIL emulation mode.

Along with usual emulation, there is a possibility to record and replay mode:

aets to list all current ESIL R&R sessions

aets+ to create a new one

aesb to step back in the current ESIL R&R session

More about this operation mode you can read in Reverse Debugging chapter.

Emulation in analysis loop

Apart from the manual emulation mode, it can be used automatically in the analysis loop. For example,
the aaaa command performs the ESIL emulation stage along with others. To disable or enable its
usage you can use anal.esil configuration variable. There is one more important option, though
setting it might be quite dangerous, especially in the case of malware - emu.write which allows ESIL
VM to modify memory. Sometimes it is required though, especially in the process of deobfuscating or
unpacking code.

To show the process of emulation you can set asm.emu variable, which will show calculated register
and memory values in disassembly comments:

182
Emulation

[0x00001660]> e asm.emu=true
[0x00001660]> pdf
. (fcn) fcn.00001660 40
│ fcn.00001660 ();
│ ; CALL XREF from 0x00001713 (entry2.fini)
│ 0x00001660 lea rdi, obj.__progname ; 0x207220 ; rdi=0x207220 -> 0x464c457f
│ 0x00001667 push rbp ; rsp=0xfffffffffffffff8
│ 0x00001668 lea rax, obj.__progname ; 0x207220 ; rax=0x207220 -> 0x464c457f
│ 0x0000166f cmp rax, rdi ; zf=0x1 -> 0x2464c45 ; cf=0x0 ; pf=0x1 -> 0x2
464c45 ; sf=0x0 ; of=0x0
│ 0x00001672 mov rbp, rsp ; rbp=0xfffffffffffffff8
│ .─< 0x00001675 je 0x1690 ; rip=0x1690 -> 0x1f0fc35d ; likely
│ │ 0x00001677 mov rax, qword [reloc._ITM_deregisterTMCloneTable] ; [0x206fd8:8]=0 ;
rax=0x0
│ │ 0x0000167e test rax, rax ; zf=0x1 -> 0x2464c45 ; pf=0x1 -> 0x2464c45 ;
sf=0x0 ; cf=0x0 ; of=0x0
│.──< 0x00001681 je 0x1690 ; rip=0x1690 -> 0x1f0fc35d ; likely
│││ 0x00001683 pop rbp ; rbp=0xffffffffffffffff -> 0x4c457fff ; rsp=0
x0
│││ 0x00001684 jmp rax ; rip=0x0 ..
│``─> 0x00001690 pop rbp ; rbp=0x10102464c457f ; rsp=0x8 -> 0x464c457f
` 0x00001691 ret ; rip=0x0 ; rsp=0x10 -> 0x3e0003

Note here likely comments, which indicates that ESIL emulation predicted for particular conditional
jump to happen.

Apart from the basic ESIL VM setup, you can change the behavior with other options located in emu.
and esil. configuration namespaces.

For manipulating ESIL working with memory and stack you can use the following options:

esil.stack to enable or disable temporary stack for asm.emu mode

esil.stack.addr to set stack address in ESIL VM (like aeim command)

esil.stack.size to set stack size in ESIL VM (like aeim command)

esil.stack.depth limits the number of PUSH operations into the stack

esil.romem specifies read-only access to the ESIL memory

esil.fillstack and esil.stack.pattern allows you to use a various pattern for filling ESIL

VM stack upon initialization

esil.nonull when set stops ESIL execution upon NULL pointer read or write.

183
Symbols information

Symbols
Radare2 automatically parses available imports and exports sections in the binary, but moreover, it can
load additional debugging information if present. Two main formats are supported: DWARF and PDB
(for Windows binaries). Note that, unlike many tools radare2 doesn't rely on Windows API to parse
PDB files, thus they can be loaded on any other supported platform - e.g. Linux or OS X.

DWARF debug info loads automatically by default because usually it's stored right in the executable
file. PDB is a bit of a different beast - it is always stored as a separate binary, thus the different logic of
handling it.

At first, one of the common scenarios is to analyze the file from Windows distribution. In this case, all
PDB files are available on the Microsoft server, which is by default is in options. See all pdb options in
radare2:

pdb.autoload = 0
pdb.extract = 1
pdb.server = https://msdl.microsoft.com/download/symbols
pdb.useragent = Microsoft-Symbol-Server/6.11.0001.402

Using the variable pdb.server you can change the address where radare2 will try to download the
PDB file by the GUID stored in the executable header. Usually, there is no reason to change default
pdb.useragent , but who knows where could it be handy?

Because those PDB files are stored as "cab" archives on the server, pdb.extract=1 says to
automatically extract them.

Note that for the automatic downloading to work you need "cabextract" tool, and wget/curl installed.

Sometimes you don't need to do that from the radare2 itself, thus - two handy rabin2 options:

-P show debug/pdb information

-PP download pdb file for binary

where -PP automatically downloads the pdb for the selected binary, using those pdb.* config
options. -P will dump the contents of the PDB file, which is useful sometimes for a quick
understanding of the symbols stored in it.

184
Symbols information

Apart from the basic scenario of just opening a file, PDB information can be additionally manipulated
by the id commands:

Where idpi is basically the same as rabin2 -P . Note that idp can be also used not only in the
static analysis mode, but also in the debugging mode, even if connected via WinDbg.

For simplifying the loading PDBs, especially for the processes with many linked DLLs, radare2 can
autoload all required PDBs automatically - you need just set the e pdb.autoload=true option. Then if
you load some file in debugging mode in Windows, using r2 -d file.exe or r2 -d 2345 (attach to
pid 2345), all related PDB files will be loaded automatically.

DWARF information loading, on the other hand, is completely automated. You don't need to run any
commands/change any options:

r2 `which rabin2`
[0x00002437 8% 300 /usr/local/bin/rabin2]> pd $r
0x00002437 jne 0x2468 ;[1]
0x00002439 cmp qword reloc.__cxa_finalize_224, 0
0x00002441 push rbp
0x00002442 mov rbp, rsp
0x00002445 je 0x2453 ;[2]
0x00002447 lea rdi, obj.__dso_handle ; 0x207c40 ; "@| "
0x0000244e call 0x2360 ;[3]
0x00002453 call sym.deregister_tm_clones ;[4]
0x00002458 mov byte [obj.completed.6991], 1 ; obj.__TMC_END__ ; [0x2082f0:1]=0
0x0000245f pop rbp
0x00002460 ret
0x00002461 nop dword [rax]
0x00002468 ret
0x0000246a nop word [rax + rax]
;-- entry1.init:
;-- frame_dummy:
0x00002470 push rbp
0x00002471 mov rbp, rsp
0x00002474 pop rbp
0x00002475 jmp sym.register_tm_clones ;[5]
;-- blob_version:

185
Symbols information

0x0000247a push rbp ; ../blob/version.c:18

0x0000247b mov rbp, rsp
0x0000247e sub rsp, 0x10
0x00002482 mov qword [rbp - 8], rdi
0x00002486 mov eax, 0x32 ; ../blob/version.c:24 ; '2'
0x0000248b test al, al ; ../blob/version.c:19
0x0000248d je 0x2498 ;[6]
0x0000248f lea rax, str.2.0.1_182_gf1aa3aa4d ; 0x60b8 ; "2.0.1-182-gf1aa3aa4d"
0x00002496 jmp 0x249f ;[7]
0x00002498 lea rax, 0x000060cd
0x0000249f mov rsi, qword [rbp - 8]
0x000024a3 mov r8, rax
0x000024a6 mov ecx, 0x40 ; section_end.ehdr
0x000024ab mov edx, 0x40c0
0x000024b0 lea rdi, str._s_2.1.0_git__d___linux_x86__d_git._s_n ; 0x60d0 ; "%s 2.1.0-gi
t %d @ linux-x86-%d git.%s\n"
0x000024b7 mov eax, 0
0x000024bc call 0x2350 ;[8]
0x000024c1 mov eax, 0x66 ; ../blob/version.c:25 ; 'f'
0x000024c6 test al, al
0x000024c8 je 0x24d6 ;[9]
0x000024ca lea rdi, str.commit:_f1aa3aa4d2599c1ad60e3ecbe5f4d8261b282385_build:_2017_11
_06__12:18:39 ; ../blob/version.c:26 ; 0x60f8 ; "commit: f1aa3aa4d2599c1ad60e3ecbe5f4d82
61b282385 build: 2017-11-06__1
0x000024d1 call sym.imp.puts ;[?]
0x000024d6 mov eax, 0 ; ../blob/version.c:28
0x000024db leave ; ../blob/version.c:29
0x000024dc ret
;-- rabin_show_help:
0x000024dd push rbp ; .//rabin2.c:27

As you can see, it loads function names and source line information.

186
Signatures

Signatures
Radare2 has its own format of the signatures, allowing to both load/apply and create them on the fly.
They are available under the z command namespace:

To load the created signature file you need to load it from SDB file using zo command or from the
compressed SDB file using zoz command.

To create signature you need to make function first, then you can create it from the function:

r2 /bin/ls
[0x000051c0]> aaa # this creates functions, including 'entry0'
[0x000051c0]> zaf entry0 entry
[0x000051c0]> z
entry:
bytes: 31ed4989d15e4889e24883e4f050544c............48............48............ff.....
.....f4
graph: cc=1 nbbs=1 edges=0 ebbs=1
offset: 0x000051c0
[0x000051c0]>

As you can see it made a new signature with a name entry from a function entry0 . You can show it
in JSON format too, which can be useful for scripting:

187
Signatures

[0x000051c0]> zj~{}
[
{
"name": "entry",
"bytes": "31ed4989d15e4889e24883e4f050544c............48............48............ff
..........f4",
"graph": {
"cc": "1",
"nbbs": "1",
"edges": "0",
"ebbs": "1"
},
"offset": 20928,
"refs": [
]
}
]
[0x000051c0]>

To remove it just run z-entry But if you want to save all created signatures, you need to save it into
the SDB file using command zos myentry . Then we can apply them. Lets open a file again:

r2 /bin/ls
-- Log On. Hack In. Go Anywhere. Get Everything.
[0x000051c0]> zo myentry
[0x000051c0]> z
entry:
bytes: 31ed4989d15e4889e24883e4f050544c............48............48............ff.....
.....f4
graph: cc=1 nbbs=1 edges=0 ebbs=1
offset: 0x000051c0
[0x000051c0]>

This means that the signatures were successfully loaded from the file myentry and now we can search
matching functions:

[0x000051c0]> zc
[+] searching 0x000051c0 - 0x000052c0
[+] searching function metrics
hits: 1
[0x000051c0]>

188
Signatures

Note that zc command just checks the signatures against the current address. To search signatures
across the all file we need to do a bit different thing. There is an important moment though, if we just
run it "as is" - it wont find anything:

[0x000051c0]> z/
[+] searching 0x0021dfd0 - 0x002203e8
[+] searching function metrics
hits: 0
[0x000051c0]>

Note the searching address - this is because we need to adjust the searching range first:

[0x000051c0]> e search.in=io.section
[0x000051c0]> z/
[+] searching 0x000038b0 - 0x00015898
[+] searching function metrics
hits: 1
[0x000051c0]>

We are setting the search mode to io.section (it was file by default) to search in the current
section (assuming we are currently in the .text section of course). Now we can check, what radare2
found for us:

[0x000051c0]> pd 5
;-- entry0:
;-- sign.bytes.entry_0:
0x000051c0 31ed xor ebp, ebp
0x000051c2 4989d1 mov r9, rdx
0x000051c5 5e pop rsi
0x000051c6 4889e2 mov rdx, rsp
0x000051c9 4883e4f0 and rsp, 0xfffffffffffffff0
[0x000051c0]>

Here we can see the comment of entry0 , which is taken from the ELF parsing, but also the
sign.bytes.entry_0 , which is exactly the result of matching signature.

Signatures configuration stored in the zign. config vars' namespace:

189
Signatures

[0x000051c0]> e zign.
zign.bytes = true
zign.graph = true
zign.maxsz = 500
zign.mincc = 10
zign.minsz = 16
zign.offset = true
zign.prefix = sign
zign.refs = true
[0x000051c0]>

190
Graph commands

Graph commands
When analyzing data it is usually handy to have different ways to represent it in order to get new
perspectives to allow the analyst to understand how different parts of the program interact.

Representing basic block edges, function calls, string references as graphs show a very clear view of
this information.

Radare2 supports various types of graph available through commands starting with ag :

The structure of the commands is as follows: ag <graph type> <output format> .

For example, agid displays the imports graph in dot format, while aggj outputs the custom graph in
JSON format.

191
Graph commands

Here's a short description for every output format available:

Ascii Art ** (e.g. agf )

Displays the graph directly to stdout using ASCII art to represent blocks and edges.

Warning: displaying large graphs directly to stdout might prove to be computationally expensive and
will make r2 not responsive for some time. In case of a doubt, prefer using the interactive view
(explained below).

Interactive Ascii Art (e.g. agfv )

Displays the ASCII graph in an interactive view similar to VV which allows to move the screen, zoom
in / zoom out, ...

Tiny Ascii Art (e.g. agft )

Displays the ASCII graph directly to stdout in tiny mode (which is the same as reaching the maximum
zoom out level in the interactive view).

Graphviz dot (e.g. agfd )

Prints the dot source code representing the graph, which can be interpreted by programs such as
graphviz or online viewers like this

JSON (e.g. agfj )

Prints a JSON string representing the graph.

In case of the f format (basic blocks of function), it will have detailed information about the
function and will also contain the disassembly of the function (use J format for the formatted
disassembly.

In all other cases, it will only have basic information about the nodes of the graph (id, title, body,
and edges).

Graph Modelling Language (e.g. agfg )

Prints the GML source code representing the graph, which can be interpreted by programs such as yEd

192
Graph commands

SDB key-value (e.g. agfk )

Prints key-value strings representing the graph that was stored by sdb (radare2's string database).

R2 custom graph commands (e.g. agf* )

Prints r2 commands that would recreate the desired graph. The commands to construct the graph are
agn [title] [body] to add a node and age [title1] [title2] to add an edge. The [body] field

can be expressed in base64 to include special formatting (such as newlines).

To easily execute the printed commands, it is possible to prepend a dot to the command ( .agf* ).

Web / image (e.g. agfw )

Radare2 will convert the graph to dot format, use the dot program to convert it to a .gif image and
then try to find an already installed viewer on your system ( xdg-open , open , ...) and display the
graph there.

The extension of the output image can be set with the graph.extension config variable. Available
extensions are png, jpg, gif, pdf, ps .

Note: for particularly large graphs, the most recommended extension is svg as it will produce images
of much smaller size

If graph.web config variable is enabled, radare2 will try to display the graph using the browser (this
feature is experimental and unfinished, and disabled by default.)

193
Scripting

Scripting
Radare2 provides a wide set of a features to automate boring work. It ranges from the simple
sequencing of the commands to the calling scripts/another programs via IPC (Inter-Process
Communication), called r2pipe.

As mentioned a few times before there is an ability to sequence commands using ; semicolon
operator.

[0x00404800]> pd 1 ; ao 1
0x00404800 b827e66100 mov eax, 0x61e627 ; "tab"
address: 0x404800
opcode: mov eax, 0x61e627
prefix: 0
bytes: b827e66100
ptr: 0x0061e627
refptr: 0
size: 5
type: mov
esil: 6415911,rax,=
stack: null
family: cpu
[0x00404800]>

It simply runs the second command after finishing the first one, like in a shell.

The second important way to sequence the commands is with a simple pipe |

ao|grep address

Note, the | pipe only can pipe output of r2 commands to external (shell) commands, like system
programs or builtin shell commands. There is a similar way to sequence r2 commands, using the
backtick operator `command` . The quoted part will undergo command substitution and the output will
be used as an argument of the command line.

For example, we want to see a few bytes of the memory at the address referred to by the 'mov eax, addr'
instruction. We can do that without jumping to it, using a sequence of commands:

194
Scripting

[0x00404800]> pd 1
0x00404800 b827e66100 mov eax, 0x61e627 ; "tab"
[0x00404800]> ao
address: 0x404800
opcode: mov eax, 0x61e627
prefix: 0
bytes: b827e66100
ptr: 0x0061e627
refptr: 0
size: 5
type: mov
esil: 6415911,rax,=
stack: null
family: cpu
[0x00404800]> ao~ptr[1]
0x0061e627
0
[0x00404800]> px 10 @ `ao~ptr[1]`
- offset - 0 1 2 3 4 5 6 7 8 9 A B C D E F 0123456789ABCDEF
0x0061e627 7461 6200 2e69 6e74 6572 tab..inter
[0x00404800]>

And of course it's possible to redirect the output of an r2 command into a file, using the > and >>
commands

[0x00404800]> px 10 @ `ao~ptr[1]` > example.txt

[0x00404800]> px 10 @ `ao~ptr[1]` >> example.txt

The ?$? command describes several helpful variables you can use to do similar actions even more
easily, like the $v "immediate value" variable, or the $m opcode memory reference variable.

195
Loops

Loops
One of the most common task in automation is looping through something, there are multiple ways to
do this in radare2.

We can loop over flags:

@@ flagname-regex

For example, we want to see function information with afi command:

[0x004047d6]> afi
#
offset: 0x004047d0
name: entry0
size: 42
realsz: 42
stackframe: 0
call-convention: amd64
cyclomatic-complexity: 1
bits: 64
type: fcn [NEW]
num-bbs: 1
edges: 0
end-bbs: 1
call-refs: 0x00402450 C
data-refs: 0x004136c0 0x00413660 0x004027e0
code-xrefs:
data-xrefs:
locals:0
args: 0
diff: type: new
[0x004047d6]>

Now let's say, for example, that we'd like see a particular field from this output for all functions found
by analysis. We can do that with a loop over all function flags (whose names begin with fcn. ):

[0x004047d6]> afi @@ fcn.* ~name

This command will extract the name field from the afi output of every flag with a name matching
the regexp fcn.* .

196
Loops

We can also loop over a list of offsets, using the following syntax:

@@=1 2 3 ... N

For example, say we want to see the opcode information for 2 offsets: the current one, and at current +
2:

[0x004047d6]> ao @@=$$ $$+2

address: 0x4047d6
opcode: mov rdx, rsp
prefix: 0
bytes: 4889e2
refptr: 0
size: 3
type: mov
esil: rsp,rdx,=
stack: null
family: cpu
address: 0x4047d8
opcode: loop 0x404822
prefix: 0
bytes: e248
refptr: 0
size: 2
type: cjmp
esil: 1,rcx,-=,rcx,?{,4212770,rip,=,}
jump: 0x00404822
fail: 0x004047da
stack: null
cond: al
family: cpu
[0x004047d6]>

Note we're using the $$ variable which evaluates to the current offset. Also note that $$+2 is
evaluated before looping, so we can use the simple arithmetic expressions.

A third way to loop is by having the offsets be loaded from a file. This file should contain one offset per
line.

197
Loops

[0x004047d0]> ?v $$ > offsets.txt

[0x004047d0]> ?v $$+2 >> offsets.txt
[0x004047d0]> !cat offsets.txt
4047d0
4047d2
[0x004047d0]> pi 1 @@.offsets.txt
xor ebp, ebp
mov r9, rdx

radare2 also offers various foreach constructs for looping. One of the most useful is for looping
through all the instructions of a function:

[0x004047d0]> pdf
╒ (fcn) entry0 42
│; UNKNOWN XREF from 0x00400018 (unk)
│; DATA XREF from 0x004064bf (sub.strlen_460)
│; DATA XREF from 0x00406511 (sub.strlen_460)
│; DATA XREF from 0x0040b080 (unk)
│; DATA XREF from 0x0040b0ef (unk)
│0x004047d0 xor ebp, ebp
│0x004047d2 mov r9, rdx
│0x004047d5 pop rsi
│0x004047d6 mov rdx, rsp
│0x004047d9 and rsp, 0xfffffffffffffff0
│0x004047dd push rax
│0x004047de push rsp
│0x004047df mov r8, 0x4136c0
│0x004047e6 mov rcx, 0x413660 ; "AWA..AVI..AUI..ATL.%.. "
0A..AVI..AUI.
│0x004047ed mov rdi, main ; "AWAVAUATUH..S..H...." @
0
│0x004047f4 call sym.imp.__libc_start_main
╘0x004047f9 hlt
[0x004047d0]> pi 1 @@i
mov r9, rdx
pop rsi
mov rdx, rsp
and rsp, 0xfffffffffffffff0
push rax
push rsp
mov r8, 0x4136c0
mov rcx, 0x413660
mov rdi, main
call sym.imp.__libc_start_main
hlt

198
Loops

In this example the command pi 1 runs over all the instructions in the current function (entry0).
There are other options too (not complete list, check @@? for more information):

@@k sdbquery - iterate over all offsets returned by that sdbquery

@@t - iterate over on all threads (see dp)

@@b - iterate over all basic blocks of current function (see afb)

@@f - iterate over all functions (see aflq)

The last kind of looping lets you loop through predefined iterator types:

symbols
imports
registers
threads
comments
functions
flags

This is done using the @@@ command. The previous example of listing information about functions can
also be done using the @@@ command:

[0x004047d6]> afi @@@ functions ~name

This will extract name field from afi output and will output a huge list of function names. We can
choose only the second column, to remove the redundant name: on every line:

[0x004047d6]> afi @@@ functions ~name[1]

199
Macros

Macros
Apart from simple sequencing and looping, radare2 allows to write simple macros, using this
construction:

[0x00404800]> (qwe, pd 4, ao)

This will define a macro called 'qwe' which runs sequentially first 'pd 4' then 'ao'. Calling the macro
using syntax .(macro) is simple:

[0x00404800]> (qwe, pd 4, ao)

[0x00404800]> .(qwe)
0x00404800 mov eax, 0x61e627 ; "tab"
0x00404805 push rbp
0x00404806 sub rax, section_end.LOAD1
0x0040480c mov rbp, rsp

address: 0x404800
opcode: mov eax, 0x61e627
prefix: 0
bytes: b827e66100
ptr: 0x0061e627
refptr: 0
size: 5
type: mov
esil: 6415911,rax,=
stack: null
family: cpu
[0x00404800]>

To list available macroses simply call (* :

[0x00404800]> (*
(qwe , pd 4, ao)

And if want to remove some macro, just add '-' before the name:

[0x00404800]> (-qwe)
Macro 'qwe' removed.
[0x00404800]>

200
Macros

Moreover, it's possible to create a macro that takes arguments, which comes in handy in some simple
scripting situations. To create a macro that takes arguments you simply add them to macro definition.
Be sure, if you're using characters like ';', to quote the whole command for proper parsing.

[0x00404800]
[0x004047d0]> "(foo x y,pd $0; s +$1)"
[0x004047d0]> .(foo 5 6)
;-- entry0:
0x004047d0 xor ebp, ebp
0x004047d2 mov r9, rdx
0x004047d5 pop rsi
0x004047d6 mov rdx, rsp
0x004047d9 and rsp, 0xfffffffffffffff0
[0x004047d6]>

As you can see, the arguments are named by index, starting from 0: $0, $1, ...

201
R2pipe

R2pipe
The r2pipe api was initially designed for NodeJS in order to support reusing the web's r2.js API from
the commandline. The r2pipe module permits interacting with r2 instances in different methods:

spawn pipes (r2 -0)

http queries (cloud friendly)
tcp socket (r2 -c)

pipe spawn async http tcp rap json

nodejs x x x x x - x
python x x - x x x x
swift x x x x - - x
dotnet x x x x - - -
haskell x x - x - - x
java - x - x - - -
golang x x - - - - x
ruby x x - - - - x
rust x x - - - - x
vala - x x - - - -
erlang x x - - - - -
newlisp x - - - - - -
dlang x - - - - - x
perl x - - - - - -

Examples

Python
$ pip install r2pipe

import r2pipe

r2 = r2pipe.open("/bin/ls")
r2.cmd('aa')
print(r2.cmd("afl"))
print(r2.cmdj("aflj")) # evaluates JSONs and returns an object

202
R2pipe

NodeJS
Use this command to install the r2pipe bindings

$ npm install r2pipe

Here's a sample hello world

const r2pipe = require('r2pipe');

r2pipe.open('/bin/ls', (err, res) => {
if (err) {
throw err;
}
r2.cmd ('af @ entry0', function (o) {
r2.cmd ("pdf @ entry0", function (o) {
console.log (o);
r.quit ()
});
});
});

Checkout the GIT repository for more examples and details.

https://github.com/radare/radare2-r2pipe/blob/master/nodejs/r2pipe/README.md

Go
$ r2pm -i r2pipe-go

https://github.com/radare/r2pipe-go

package main

import (
"fmt"
"github.com/radare/r2pipe-go"
)

203
R2pipe

func main() {
r2p, err := r2pipe.NewPipe("/bin/ls")
if err != nil {
panic(err)
}
defer r2p.Close()
buf1, err := r2p.Cmd("?E Hello World")
if err != nil {
panic(err)
}
fmt.Println(buf1)
}

Rust
$ cat Cargo.toml
...
[dependencies]
r2pipe = "*"

#[macro_use]
extern crate r2pipe;
use r2pipe::R2Pipe;
fn main() {
let mut r2p = open_pipe!(Some("/bin/ls")).unwrap();
println!("{:?}", r2p.cmd("?e Hello World"));
let json = r2p.cmdj("ij").unwrap();
println!("{}", json.pretty());
println!("ARCH {}", json.find_path(&["bin","arch"]).unwrap());
r2p.close();
}

Ruby
$ gem install r2pipe

204
R2pipe

require 'r2pipe'
puts 'r2pipe ruby api demo'
puts '===================='
r2p = R2Pipe.new '/bin/ls'
puts r2p.cmd 'pi 5'
puts r2p.cmd 'pij 1'
puts r2p.json(r2p.cmd 'pij 1')
puts r2p.cmd 'px 64'
r2p.quit

Perl
#!/usr/bin/perl

use R2::Pipe;
use strict;

my $r = R2::Pipe->new ("/bin/ls");
print $r->cmd ("pd 5")."\n";
print $r->cmd ("px 64")."\n";
$r->quit ();

Erlang

205
R2pipe

#!/usr/bin/env escript
%% -*- erlang -*-
%%! -smp enable

%% -sname hr
-mode(compile).

-export([main/1]).

main(_Args) ->
%% adding r2pipe to modulepath, set it to your r2pipe_erl location
R2pipePATH = filename:dirname(escript:script_name()) ++ "/ebin",
true = code:add_pathz(R2pipePATH),

%% initializing the link with r2

H = r2pipe:init(lpipe),

%% all work goes here

io:format("~s", [r2pipe:cmd(H, "i")]).

Haskell
import R2pipe
import qualified Data.ByteString.Lazy as L

showMainFunction ctx = do
cmd ctx "s main"
L.putStr =<< cmd ctx "pD `fl $$`"

main = do
-- Run r2 locally
open "/bin/ls" >>= showMainFunction
-- Connect to r2 via HTTP (e.g. if "r2 -qc=h /bin/ls" is running)
open "http://127.0.0.1:9090" >>= showMainFunction

Dotnet

206
R2pipe

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using r2pipe;

namespace LocalExample {
class Program {
static void Main(string[] args) {
#if __MonoCS__
using(IR2Pipe pipe = new R2Pipe("/bin/ls")) {
#else
using (IR2Pipe pipe = new R2Pipe(@"C:\Windows\notepad.exe",
@"C:\radare2\radare2.exe")) {
#endif
Console.WriteLine("Hello r2! " + pipe.RunCommand("?V"));
Task<string> async = pipe.RunCommandAsync("?V");
Console.WriteLine("Hello async r2!" + async.Result);
QueuedR2Pipe qr2 = new QueuedR2Pipe(pipe);
qr2.Enqueue(new R2Command("x", (string result) => {
Console.WriteLine("Result of x:\n {0}", result); }));
qr2.Enqueue(new R2Command("pi 10", (string result) => {
Console.WriteLine("Result of pi 10:\n {0}", result); }));
qr2.ExecuteCommands();
}
}
}
}

Java

207
R2pipe

import org.radare.r2pipe.R2Pipe;

public class Test {

public static void main (String[] args) {
try {
R2Pipe r2p = new R2Pipe ("/bin/ls");
// new R2Pipe ("http://cloud.rada.re/cmd/", true);
System.out.println (r2p.cmd ("pd 10"));
System.out.println (r2p.cmd ("px 32"));
r2p.quit();
} catch (Exception e) {
System.err.println (e);
}
}
}

Swift
if let r2p = R2Pipe(url:nil) {
r2p.cmd ("?V", closure:{
(str:String?) in
if let s = str {
print ("Version: \(s)");
exit (0);
} else {
debugPrint ("R2PIPE. Error");
exit (1);
}
});
NSRunLoop.currentRunLoop().run();
} else {
print ("Needs to run from r2")
}

Vala

208
R2pipe

public static int main (string[] args) {

MainLoop loop = new MainLoop ();
var r2p = new R2Pipe ("/bin/ls");
r2p.cmd ("pi 4", (x) => {
stdout.printf ("Disassembly:\n%s\n", x);
r2p.cmd ("ie", (x) => {
stdout.printf ("Entrypoint:\n%s\n", x);
r2p.cmd ("q");
});
});
ChildWatch.add (r2p.child_pid, (pid, status) => {
Process.close_pid (pid);
loop.quit ();
});
loop.run ();
return 0;
}

NewLisp
(load "r2pipe.lsp")
(println "pd 3:\n" (r2pipe:cmd "pd 3"))
(exit)

Dlang
import std.stdio;
import r2pipe;

void main() {
auto r2 = r2pipe.open ();
writeln ("Hello "~ r2.cmd("?e World"));
writeln ("Hello "~ r2.cmd("?e Works"));

string uri = r2.cmdj("ij")["core"]["uri"].str;

writeln ("Uri: ",uri);
}

209
Debugger

Debugger
Debuggers are implemented as IO plugins. Therefore, radare can handle different URI types for
spawning, attaching and controlling processes. The complete list of IO plugins can be viewed with r2
-L . Those that have "d" in the first column ("rwd") support debugging. For example:

r_d debug Debug a program or pid. dbg:///bin/ls, dbg://1388 (LGPL3)

rwd gdb Attach to gdbserver, 'qemu -s', gdb://localhost:1234 (LGPL3)

There are different backends for many target architectures and operating systems, e.g., GNU/Linux,
Windows, MacOS X, (Net,Free,Open)BSD and Solaris.

Process memory is treated as a plain file. All mapped memory pages of a debugged program and its
libraries can be read and interpreted as code or data structures.

Communication between radare and the debugger IO layer is wrapped into system() calls, which
accept a string as an argument, and executes it as a command. An answer is then buffered in the output
console, its contents can be additionally processed by a script. Access to the IO system is achieved with
=! . Most IO plugins provide help with =!? or =!help . For example:

$ r2 -d /bin/ls
...
[0x7fc15afa3cc0]> =!help
Usage: =!cmd args
=!ptrace - use ptrace io
=!mem - use /proc/pid/mem io if possible
=!pid - show targeted pid
=!pid <#> - select new pid

In general, debugger commands are portable between architectures and operating systems. Still, as
radare tries to support the same functionality for all target architectures and operating systems, certain
things have to be handled separately. They include injecting shellcodes and handling exceptions. For
example, in MIPS targets there is no hardware-supported single-stepping feature. In this case, radare2
provides its own implementation for single-step by using a mix of code analysis and software
breakpoints.

To get basic help for the debugger, type 'd?':

210
Debugger

Usage: d # Debug commands

db[?] Breakpoints commands
dbt[?] Display backtrace based on dbg.btdepth and dbg.btalgo
dc[?] Continue execution
dd[?] File descriptors (!fd in r1)
de[-sc] [rwx] [rm] [e] Debug with ESIL (see de?)
dg <file> Generate a core-file (WIP)
dH [handler] Transplant process to a new handler
di[?] Show debugger backend information (See dh)
dk[?] List, send, get, set, signal handlers of child
dL [handler] List or set debugger handler
dm[?] Show memory maps
do[?] Open process (reload, alias for 'oo')
doo[args] Reopen in debugger mode with args (alias for 'ood')
dp[?] List, attach to process or thread id
dr[?] Cpu registers
ds[?] Step, over, source line
dt[?] Display instruction traces (dtr=reset)
dw <pid> Block prompt until pid dies
dx[?] Inject and run code on target process (See gs)

To restart your debugging session, you can type oo or oo+ , depending on desired behavior.

oo reopen current file (kill+fork in debugger)

oo+ reopen current file in read-write

211
Getting Started

Getting Started

Small session in radare2 debugger

r2 -d /bin/ls : Opens radare2 with file /bin/ls in debugger mode using the radare2 native

debugger, but does not run the program. You’ll see a prompt (radare2) - all examples are from this
prompt.

db flag : place a breakpoint at flag, where flag can be either an address or a function name

db - flag : remove the breakpoint at flag, where flag can be either an address or a function name

db : show list of breakpoint

dc : run the program

dr : Show registers state

drr : Show registers references (telescoping) (like peda)

ds : Step into instruction

dso : Step over instruction

dbt : Display backtrace

dm : Show memory maps

dk <signal> : Send KILL signal to child

ood : reopen in debug mode

ood arg1 arg2 : reopen in debug mode with arg1 and arg2

212
Migration from ida, GDB or WinDBG

Migration from ida, GDB or WinDBG

How to run the program using the debugger

r2 -d /bin/ls - start in debugger mode => [video]

How do I attach/detach to running process ?

(gdb -p)
r2 -d <pid> - attach to process

r2 ptrace://pid - same as above, but only for io (not debugger backend hooked)

[0x7fff6ad90028]> o-225 - close fd=225 (listed in o~[1]:0 )

r2 -D gdb gdb://localhost:1234 - attach to gdbserver

How to set args/environment variable/load a

specific libraries for the debugging session of
radare
Use rarun2 ( libpath=$PWD:/tmp/lib , arg2=hello , setenv=FOO=BAR ...) see rarun2 -h / man
rarun2

How to script radare2 ?

r2 -i <scriptfile> ... - run a script after loading the file => [video]

r2 -I <scriptfile> ... - run a script before loading the file

r2 -c $@ | awk $@ - run thru awk get asm from function => [link]

[0x80480423]> . scriptfile - interpret this file => [video]

213
Migration from ida, GDB or WinDBG

[0x80480423]> #!c - enter C repl (see #! to list all available RLang plugins) => [video], everything

have to be done in a oneliner or a .c file must be passed as an argument.

To get #!python and much more, just build radare2-bindings

How to list Source code as in gdb list ?

CL @ sym.main - though the feature is highly experimental

shortcuts
Command IDA Pro radare2 r2 (visual mode) GDB

Analysis
Automatically aaa or -A (aaaa
Analysis of launched when or -AA for even
opening a experimental
N/A N/A
everything
binary analysis)

Navigation

xref to x axt x N/A

xref from ctrl + j axf X N/A

xref to graph ? agt [offset] ? N/A

xref from graph ? agf [offset] ? N/A

list functions alt + 1 afl;is t N/A

listing alt + 2 pdf p N/A

hex mode alt + 3 pxa P N/A

imports alt + 6 ii :ii N/A

exports alt + 7 is~FUNC ? N/A

follow jmp/call enter s offset enter or 0 - 9 N/A

undo seek esc s- u N/A

redo seek ctrl+enter s+ U N/A

show graph space agv V N/A

214
Migration from ida, GDB or WinDBG

Edit

rename n afn dr N/A

graph view space agv V N/A

define as data d Cd [size] dd , db , dw , dW N/A

define as code c C- [size] d- or du N/A

define as undefined u C- [size] d- or du N/A

define as string A Cs [size] ds N/A

define as struct Alt+Q Cf [size] dF N/A

Debugger

Start Process/ F9 dc F9 r and

Continue execution

Terminate Process Ctrl+F2 dk 9 ? kill

Detach ? o- ? detach

step into F7 ds s n

step into 4
? ds 4 F7 n 4
instructions

step over F8 dso S s

step until a specific

? dsu <addr> ? s
address

Run until return Ctrl+F7 dcr ? finish

Run until cursor F4 #249 #249 N/A

Show Backtrace ? dbt ? bt

On register Shown in Visual

display Register dr all
registers
Windows mode

On register Shown in Visual
display eax dr?eax registers
Windows mode eax

display old state of

? dro ? ?
all registers

afi $$ - display

215
Migration from ida, GDB or WinDBG

display function function

? information of ? ?
addr + N
current offset
( $$ )

display frame state ? pxw rbp-rsp@rsp ? i f

How to step until

? dsi ? ?
condition is true

Update a register
? dr rip=0x456 ? $rip=0x456
value

Disassembly

disassembly
N/A pd Vp disas
forward

disassembly N
N/A pd X Vp x/i
instructions

disassembly N disas <a-o>

N/A pd -X Vp
<a>
(backward)

Information on
the bin

Menu iS or S maint info

Sections/regions sections N/A
(append j for json) sections

Load symbol file

asm.dwarf.file , add-symbol-
Sections/regions pdb menu N/A
pdb.XX ) file

BackTrace

Stack Trace N/A dbt N/A bt

Stack Trace in Json N/A dbtj N/A

dbt
Partial Backtrace (
N/A dbg.btdepth N/A bt
(innermost) dbg.btalgo )

dbt
Partial Backtrace (
N/A dbg.btdepth N/A bt -
(outermost) dbg.btalgo )

Stacktrace for all
N/A dbt@t N/A apply all
threads bt

216
Migration from ida, GDB or WinDBG

Breakpoints

Breakpoint list Ctrl+Alt+B db ? breakpoints

add breakpoint F2 db [offset] F2 break

Threads

Switch to thread Thread menu dp N/A thread <N>

Frames

any bt
Frame Numbers N/A ? N/A command

Select Frame N/A ? N/A frame

Parameters/Locals

Display parameters N/A afv N/A info args

Display parameters N/A afv N/A locals

Display

parameters/locals N/A afvj N/A locals
in json

list addresses where

vars are N/A afvR/afvW N/A ?
accessed(R/W)

Project Related

open project Po [file] ?

save project automatic Ps [file] ?

show project Pi [file] ?

informations

Miscellaneous

Dump byte char pc? (json, C,

N/A Vpppp x/bc
array char, etc.)

options option menu e? e

Select the zone

search search menu /? with the cursor c
then /

217
Migration from ida, GDB or WinDBG

Equivalent of "set-follow-fork-mode" gdb

command
This can be done using 2 commands:

1. dcf - until a fork happen

2. then use dp to select what process you want to debug.

Common features
r2 accepts FLIRT signatures
r2 can connect to GDB, LLVM and WinDbg
r2 can write/patch in place
r2 have fortunes and [s]easter eggs[/s]balls of steel
r2 can do basic loading of ELF core files from the box and MDMP (Windows minidumps)

218
Registers

Registers
The registers are part of a user area stored in the context structure used by the scheduler. This structure
can be manipulated to get and set the values of those registers, and, for example, on Intel hosts, it is
possible to directly manipulate DR0-DR7 hardware registers to set hardware breakpoints.

There are different commands to get values of registers. For the General Purpose ones use:

[0x4A13B8C0]> dr
r15 = 0x00000000
r14 = 0x00000000
r13 = 0x00000000
r12 = 0x00000000
rbp = 0x00000000
rbx = 0x00000000
r11 = 0x00000000
r10 = 0x00000000
r9 = 0x00000000
r8 = 0x00000000
rax = 0x00000000
rcx = 0x00000000
rdx = 0x00000000
rsi = 0x00000000
rdi = 0x00000000
oeax = 0x0000003b
rip = 0x7f20bf5df630
rsp = 0x7fff515923c0

[0x7f0f2dbae630]> dr rip ; get value of 'rip'

0x7f0f2dbae630

[0x4A13B8C0]> dr rip = esp ; set 'rip' as esp

Interaction between a plugin and the core is done by commands returning radare instructions. This is
used, for example, to set flags in the core to set values of registers.

219
Registers

[0x7f0f2dbae630]> dr* ; Appending '*' will show radare commands

f r15 1 0x0
f r14 1 0x0
f r13 1 0x0
f r12 1 0x0
f rbp 1 0x0
f rbx 1 0x0
f r11 1 0x0
f r10 1 0x0
f r9 1 0x0
f r8 1 0x0
f rax 1 0x0
f rcx 1 0x0
f rdx 1 0x0
f rsi 1 0x0
f rdi 1 0x0
f oeax 1 0x3b
f rip 1 0x7fff73557940
f rflags 1 0x200
f rsp 1 0x7fff73557940

[0x4A13B8C0]> .dr* ; include common register values in flags

An old copy of registers is stored all the time to keep track of the changes done during execution of a
program being analyzed. This old copy can be accessed with oregs .

[0x7f1fab84c630]> dro
r15 = 0x00000000
r14 = 0x00000000
r13 = 0x00000000
r12 = 0x00000000
rbp = 0x00000000
rbx = 0x00000000
r11 = 0x00000000
r10 = 0x00000000
r9 = 0x00000000
r8 = 0x00000000
rax = 0x00000000
rcx = 0x00000000
rdx = 0x00000000
rsi = 0x00000000
rdi = 0x00000000
oeax = 0x0000003b
rip = 0x7f1fab84c630
rflags = 0x00000200
rsp = 0x7fff386b5080

220
Registers

Current state of registers

[0x7f1fab84c630]> dr
r15 = 0x00000000
r14 = 0x00000000
r13 = 0x00000000
r12 = 0x00000000
rbp = 0x00000000
rbx = 0x00000000
r11 = 0x00000000
r10 = 0x00000000
r9 = 0x00000000
r8 = 0x00000000
rax = 0x00000000
rcx = 0x00000000
rdx = 0x00000000
rsi = 0x00000000
rdi = 0x7fff386b5080
oeax = 0xffffffffffffffff
rip = 0x7f1fab84c633
rflags = 0x00000202
rsp = 0x7fff386b5080

Values stored in eax, oeax and eip have changed.

To store and restore register values you can just dump the output of 'dr*' command to disk and then re-
interpret it again:

[0x4A13B8C0]> dr* > regs.saved ; save registers

[0x4A13B8C0]> drp regs.saved ; restore

EFLAGS can be similarly altered. E.g., setting selected flags:

[0x4A13B8C0]> dr eflags = pst

[0x4A13B8C0]> dr eflags = azsti

You can get a string which represents latest changes of registers using drd command (diff registers):

[0x4A13B8C0]> drd
oeax = 0x0000003b was 0x00000000 delta 59
rip = 0x7f00e71282d0 was 0x00000000 delta -418217264
rflags = 0x00000200 was 0x00000000 delta 512
rsp = 0x7fffe85a09c0 was 0x00000000 delta -396752448

221
Registers

222
Memory Maps

Memory Maps
The ability to understand and manipulate the memory maps of a debugged program is important for
many different Reverse Engineering tasks. radare2 offers a rich set of commands to handle memory
maps in the binary. This includes listing the memory maps of the currently debugged binary, removing
memory maps, handling loaded libraries and more.

First, let's see the help message for dm , the command which is responsible for handling memory maps:

[0x55f2104cf620]> dm?
|Usage: dm # Memory maps commands
| dm List memory maps of target process
| dm addr size Allocate <size> bytes at <address> (anywhere if address is -1) in chil
d process
| dm= List memory maps of target process (ascii-art bars)
| dm. Show map name of current address
| dm* List memmaps in radare commands
| dm- address Deallocate memory map of <address>
| dmd[a] [file] Dump current (all) debug map region to a file (from-to.dmp) (see Sd)
| dmh[?] Show map of heap
| dmi. List closest symbol to the current address
| dmiv Show address of given symbol for given lib
| dmj List memmaps in JSON format
| dml <file> Load contents of file into the current map region (see Sl)
| dmm[?][j*] List modules (libraries, binaries loaded in memory)
| dmi [addr|libname] [symname] List symbols of target lib
| dmi* [addr|libname] [symname] List symbols of target lib in radare commands
| dmp[?] <address> <size> <perms> Change page at <address> with <size>, protection <per
ms> (rwx)
| dms[?] <id> <mapaddr> Take memory snapshot
| dms- <id> <mapaddr> Restore memory snapshot
| dmS [addr|libname] [sectname] List sections of target lib
| dmS* [addr|libname] [sectname] List sections of target lib in radare commands

In this chapter, we'll go over some of the most useful subcommands of dm using simple examples. For
the following examples, we'll use a simple helloworld program for Linux but it'll be the same for
every binary.

First things first - open a program in debugging mode:

223
Memory Maps

$ r2 -d helloworld
Process with PID 20304 started...
= attach 20304 20304
bin.baddr 0x56136b475000
Using 0x56136b475000
asm.bits 64
[0x7f133f022fb0]>

Note that we passed "helloworld" to radare2 without "./". radare2 will try to find this program in
the current directory and then in $PATH, even if no "./" is passed. This is contradictory with
UNIX systems, but makes the behaviour consistent for windows users

Let's use dm to print the memory maps of the binary we've just opened:

[0x7f133f022fb0]> dm
0x0000563a0113a000 - usr 4K s r-x /tmp/helloworld /tmp/helloworld ; map.tmp_helloworld
.r_x
0x0000563a0133a000 - usr 8K s rw- /tmp/helloworld /tmp/helloworld ; map.tmp_helloworld
.rw
0x00007f133f022000 * usr 148K s r-x /usr/lib/ld-2.27.so /usr/lib/ld-2.27.so ; map.usr_li
b_ld_2.27.so.r_x
0x00007f133f246000 - usr 8K s rw- /usr/lib/ld-2.27.so /usr/lib/ld-2.27.so ; map.usr_li
b_ld_2.27.so.rw
0x00007f133f248000 - usr 4K s rw- unk0 unk0 ; map.unk0.rw
0x00007fffd25ce000 - usr 132K s rw- [stack] [stack] ; map.stack_.rw
0x00007fffd25f6000 - usr 12K s r-- [vvar] [vvar] ; map.vvar_.r
0x00007fffd25f9000 - usr 8K s r-x [vdso] [vdso] ; map.vdso_.r_x
0xffffffffff600000 - usr 4K s r-x [vsyscall] [vsyscall] ; map.vsyscall_.r_x

For those of you who prefer a more visual way, you can use dm= to see the memory maps using an
ASCII-art bars. This will be handy when you want to see how these maps are located in the memory.

If you want to know the memory-map you are currently in, use dm. :

[0x7f133f022fb0]> dm.
0x00007f947eed9000 # 0x00007f947eefe000 * usr 148K s r-x /usr/lib/ld-2.27.so /usr/lib/
ld-2.27.so ; map.usr_lib_ld_2.27.so.r_x

Using dmm we can "List modules (libraries, binaries loaded in memory)", this is quite a handy
command to see which modules were loaded.

224
Memory Maps

[0x7fa80a19dfb0]> dmm
0x55ca23a4a000 /tmp/helloworld
0x7fa80a19d000 /usr/lib/ld-2.27.so

Note that the output of dm subcommands, and dmm specifically, might be different in various
systems and different binaries.

We can see that along with our helloworld binary itself, another library was loaded which is ld-
2.27.so . We don't see libc yet and this is because radare2 breaks before libc is loaded to memory.

Let's use dcu (debug continue until) to execute our program until the entry point of the program,
which radare flags as entry0 .

[0x7fa80a19dfb0]> dcu entry0

Continue until 0x55ca23a4a520 using 1 bpsize
hit breakpoint at: 55ca23a4a518
[0x55ca23a4a520]> dmm
0x55ca23a4a000 /tmp/helloworld
0x7fa809de1000 /usr/lib/libc-2.27.so
0x7fa80a19d000 /usr/lib/ld-2.27.so

Now we can see that libc-2.27.so was loaded as well, great!

Speaking of libc , a popular task for binary exploitation is to find the address of a specific symbol in a
library. With this information in hand, you can build, for example, an exploit which uses ROP. This can
be achieved using the dmi command. So if we want, for example, to find the address of system() in
the loaded libc , we can simply execute the following command:

[0x55ca23a4a520]> dmi libc system

514 0x00000000 0x7fa809de1000 LOCAL FILE 0 system.c
515 0x00043750 0x7fa809e24750 LOCAL FUNC 1221 do_system
4468 0x001285a0 0x7fa809f095a0 LOCAL FUNC 100 svcerr_systemerr
5841 0x001285a0 0x7fa809f095a0 LOCAL FUNC 100 svcerr_systemerr
6427 0x00043d10 0x7fa809e24d10 WEAK FUNC 45 system
7094 0x00043d10 0x7fa809e24d10 GLBAL FUNC 45 system
7480 0x001285a0 0x7fa809f095a0 GLBAL FUNC 100 svcerr_systemerr

Similar to the dm. command, with dmi. you can see the closest symbol to the current address.

Another useful command is to list the sections of a specific library. In the following example we'll list
the sections of ld-2.27.so :

225
Memory Maps

[0x55a7ebf09520]> dmS ld-2.27

[Sections]
00 0x00000000 0 0x00000000 0 ---- ld-2.27.so.
01 0x000001c8 36 0x4652d1c8 36 -r-- ld-2.27.so..note.gnu.build_id
02 0x000001f0 352 0x4652d1f0 352 -r-- ld-2.27.so..hash
03 0x00000350 412 0x4652d350 412 -r-- ld-2.27.so..gnu.hash
04 0x000004f0 816 0x4652d4f0 816 -r-- ld-2.27.so..dynsym
05 0x00000820 548 0x4652d820 548 -r-- ld-2.27.so..dynstr
06 0x00000a44 68 0x4652da44 68 -r-- ld-2.27.so..gnu.version
07 0x00000a88 164 0x4652da88 164 -r-- ld-2.27.so..gnu.version_d
08 0x00000b30 1152 0x4652db30 1152 -r-- ld-2.27.so..rela.dyn
09 0x00000fb0 11497 0x4652dfb0 11497 -r-x ld-2.27.so..text
10 0x0001d0e0 17760 0x4654a0e0 17760 -r-- ld-2.27.so..rodata
11 0x00021640 1716 0x4654e640 1716 -r-- ld-2.27.so..eh_frame_hdr
12 0x00021cf8 9876 0x4654ecf8 9876 -r-- ld-2.27.so..eh_frame
13 0x00024660 2020 0x46751660 2020 -rw- ld-2.27.so..data.rel.ro
14 0x00024e48 336 0x46751e48 336 -rw- ld-2.27.so..dynamic
15 0x00024f98 96 0x46751f98 96 -rw- ld-2.27.so..got
16 0x00025000 3960 0x46752000 3960 -rw- ld-2.27.so..data
17 0x00025f78 0 0x46752f80 376 -rw- ld-2.27.so..bss
18 0x00025f78 17 0x00000000 17 ---- ld-2.27.so..comment
19 0x00025fa0 63 0x00000000 63 ---- ld-2.27.so..gnu.warning.llseek
20 0x00025fe0 13272 0x00000000 13272 ---- ld-2.27.so..symtab
21 0x000293b8 7101 0x00000000 7101 ---- ld-2.27.so..strtab
22 0x0002af75 215 0x00000000 215 ---- ld-2.27.so..shstrtab

226
Heap

Heap
radare2's dm subcommands can also display a map of the heap which is useful for those who are
interesting in inspecting the heap and its content. Simply execute dmh to show a map of the heap:

[0x7fae46236ca6]> dmh
Malloc chunk @ 0x55a7ecbce250 [size: 0x411][allocated]
Top chunk @ 0x55a7ecbce660 - [brk_start: 0x55a7ecbce000, brk_end: 0x55a7ecbef000]

You can also see a graph layout of the heap:

[0x7fae46236ca6]> dmhg
Heap Layout
.────────────────────────────────────.
│ Malloc chunk @ 0x55a7ecbce000 │
│ size: 0x251 │
│ fd: 0x0, bk: 0x0 │
`────────────────────────────────────'
│
.───'
│
│
.─────────────────────────────────────────────.
│ Malloc chunk @ 0x55a7ecbce250 │
│ size: 0x411 │
│ fd: 0x57202c6f6c6c6548, bk: 0xa21646c726f │
`─────────────────────────────────────────────'
│
.───'
│
│
.────────────────────────────────────────────────────.
│ Top chunk @ 0x55a7ecbce660 │
│ [brk_start:0x55a7ecbce000, brk_end:0x55a7ecbef000] │
`────────────────────────────────────────────────────'

Another heap commands can be found under dmh , check dmh? for the full list.

227
Heap

[0x00000000]> dmh?
|Usage: dmh # Memory map heap
| dmh List chunks in heap segment
| dmh [malloc_state] List heap chunks of a particular arena
| dmha List all malloc_state instances in application
| dmhb Display all parsed Double linked list of main_arena's bins instanc
e
| dmhb [bin_num|bin_num:malloc_state] Display parsed double linked list of bins
instance from a particular arena
| dmhbg [bin_num] Display double linked list graph of main_arena's bin [Under develo
pemnt]
| dmhc @[chunk_addr] Display malloc_chunk struct for a given malloc chunk
| dmhf Display all parsed fastbins of main_arena's fastbinY instance
| dmhf [fastbin_num|fastbin_num:malloc_state] Display parsed single linked list in fast
binY instance from a particular arena
| dmhg Display heap graph of heap segment
| dmhg [malloc_state] Display heap graph of a particular arena
| dmhi @[malloc_state]Display heap_info structure/structures for a given arena
| dmhm List all elements of struct malloc_state of main thread (main_aren
a)
| dmhm [malloc_state] List all malloc_state instance of a particular arena
| dmht Display all parsed thead cache bins of main_arena's tcache instanc
e
| dmh? Show map heap help

228
Files

Files
The radare2 debugger allows the user to list and manipulate the file descriptors from the target process.

This is a useful feature, which is not found in other debuggers, the functionality is similar to the lsof
command line tool.

But have extra subcommands to change the seek, close or duplicate them.

So, at any time in the debugging session you can replace the stdio file descriptors to use network
sockets created by r2, or replace a network socket connection to hijack it.

This functionality is also available in r2frida by using the dd command prefixed with a backslash. In r2
you may want to see the output of dd? for proper details.

229
Reverse Debugging

Reverse Debugging
Radare2 has reverse debugger, that can seek program counter backward. (e.g. reverse-next, reverse-
continue in gdb) Firstly you need to save program state at the point that you want to start recording. The
syntax for recording is:

[0x004028a0]> dts+

You can use dts commands for recording and managing program states. After recording the states,
you can seek pc back and forth to any points after saved address. So after recording, you can try single
step back:

[0x004028a0]> 2dso
[0x004028a0]> dr rip
0x004028ae
[0x004028a0]> dsb
continue until 0x004028a2
hit breakpoint at: 4028a2
[0x004028a0]> dr rip
0x004028a2

When you run dsb , reverse debugger restore previous recorded state and execute program from it until
desired point.

Or you can also try continue back:

[0x004028a0]> db 0x004028a2
[0x004028a0]> 10dso
[0x004028a0]> dr rip
0x004028b9
[0x004028a0]> dcb
[0x004028a0]> dr rip
0x004028a2

dcb seeks program counter until hit the latest breakpoint. So once set a breakpoint, you can back to it

any time.

You can see current recorded program states using dts :

230
Reverse Debugging

[0x004028a0]> dts
session: 0 at:0x004028a0 ""
session: 1 at:0x004028c2 ""

NOTE: Program records can be saved at any moments. These are diff style format that save only
different memory area from previous. It saves memory space rather than entire dump.

And also can add comment:

[0x004028c2]> dtsC 0 program start

[0x004028c2]> dtsC 1 decryption start
[0x004028c2]> dts
session: 0 at:0x004028a0 "program start"
session: 1 at:0x004028c2 "decryption start"

You can leave notes for each records to keep in your mind. dsb and dcb commands restore the
program state from latest record if there are many records.

Program records can exported to file and of course import it. Export/Import records to/from file:

[0x004028c2]> dtst records_for_test

Session saved in records_for_test.session and dump in records_for_test.dump
[0x004028c2]> dtsf records_for_test
session: 0, 0x4028a0 diffs: 0
session: 1, 0x4028c2 diffs: 0

Moreover, you can do reverse debugging in ESIL mode. In ESIL mode, program state can be managed
by aets commands.

[0x00404870]> aets+

And step back by aesb :

[0x00404870]> aer rip

0x00404870
[0x00404870]> 5aeso
[0x00404870]> aer rip
0x0040487d
[0x00404870]> aesb
[0x00404870]> aer rip
0x00404879

231
Reverse Debugging

232
Remote Access

Remote Access Capabilities

Radare can be run locally, or it can be started as a server process which is controlled by a local radare2
process. This is possible because everything uses radare's IO subsystem which abstracts access to
system(), cmd() and all basic IO operations so to work over a network.

Help for commands useful for remote access to radare:

You can learn radare2 remote capabilities by displaying the list of supported IO plugins: radare2 -L .

A little example should make this clearer. A typical remote session might look like this:

At the remote host1:

$ radare2 rap://:1234

At the remote host2:

$ radare2 rap://:1234

233
Remote Access

At localhost:

$ radare2 -

Add hosts

[0x004048c5]> =+ rap://<host1>:1234//bin/ls
Connected to: <host1> at port 1234
waiting... ok

[0x004048c5]> =
0 - rap://<host1>:1234//bin/ls

You can open remote files in debug mode (or using any IO plugin) specifying URI when adding hosts:

[0x004048c5]> =+ =+ rap://<host2>:1234/dbg:///bin/ls
Connected to: <host2> at port 1234
waiting... ok
0 - rap://<host1>:1234//bin/ls
1 - rap://<host2>:1234/dbg:///bin/ls

To execute commands on host1:

[0x004048c5]> =0 px
[0x004048c5]> = s 0x666

To open a session with host2:

[0x004048c5]> ==1
fd:6> pi 1
...
fd:6> q

To remove hosts (and close connections):

[0x004048c5]> =-

You can also redirect radare output to a TCP or UDP server (such as nc -l ). First, Add the server with
'=+ tcp://' or '=+ udp://', then you can redirect the output of a command to be sent to the server:

234
Remote Access

[0x004048c5]> =+ tcp://<host>:<port>/
Connected to: <host> at port <port>
5 - tcp://<host>:<port>/
[0x004048c5]> =<5 cmd...

The =< command will send the output from the execution of cmd to the remote connection number N
(or the last one used if no id specified).

235
Remote GDB

Debugging with gdbserver

radare2 allows remote debugging over the gdb remote protocol. So you can run a gdbserver and connect
to it with radare2 for remote debugging. The syntax for connecting is:

$ r2 -d gdb://<host>:<port>

Note that the following command does the same, r2 will use the debug plugin specified by the uri if
found.

$ r2 -D gdb gdb://<host>:<port>

The debug plugin can be changed at runtime using the dL or Ld commands.

Or if the gdbserver is running in extended mode, you can attach to a process on the host with:

$ r2 -d gdb://<host>:<port>/<pid>

After connecting, you can use the standard r2 debug commands as normal.

radare2 does not yet load symbols from gdbserver, so it needs the binary to be locally present to load
symbols from it. In case symbols are not loaded even if the binary is present, you can try specifying the
path with e dbg.exe.path :

$ r2 -e dbg.exe.path=<path> -d gdb://<host>:<port>

If symbols are loaded at an incorrect base address, you can try specifying the base address too with e
bin.baddr :

$ r2 -e bin.baddr=<baddr> -e dbg.exe.path=<path> -d gdb://<host>:<port>

Usually the gdbserver reports the maximum packet size it supports. Otherwise, radare2 resorts to
sensible defaults. But you can specify the maximum packet size with the environment variable
R2_GDB_PKTSZ . You can also check and set the max packet size during a session with the IO system,

=! .

236
Remote GDB

$ export R2_GDB_PKTSZ=512
$ r2 -d gdb://<host>:<port>
= attach <pid> <tid>
Assuming filepath <path/to/exe>
[0x7ff659d9fcc0]> =!pktsz
packet size: 512 bytes
[0x7ff659d9fcc0]> =!pktsz 64
[0x7ff659d9fcc0]> =!pktsz
packet size: 64 bytes

The gdb IO system provides useful commands which might not fit into any standard radare2 commands.
You can get a list of these commands with =!? . (Remember, =! accesses the underlying IO plugin's
system() ).

[0x7ff659d9fcc0]> =!?
Usage: =!cmd args
=!pid - show targeted pid
=!pkt s - send packet 's'
=!monitor cmd - hex-encode monitor command and pass to target interpreter
=!detach [pid] - detach from remote/detach specific pid
=!inv.reg - invalidate reg cache
=!pktsz - get max packet size used
=!pktsz bytes - set max. packet size as 'bytes' bytes
=!exec_file [pid] - get file which was executed for current/specified pid

radare2 also provides its own gdbserver implementation:

$ r2 -
[0x00000000]> =g?
|Usage: =[g] [...] # gdb server
| gdbserver:
| =g port file [args] listen on 'port' debugging 'file' using gdbserver
| =g! port file [args] same as above, but debug protocol messages (like gdbserver --rem
ote-debug)

So you can start it as:

$ r2 -
[0x00000000]> =g 8000 /bin/radare2 -

And then connect to it like you would to any gdbserver. For example, with radare2:

237
Remote GDB

$ r2 -d gdb://localhost:8000

238
Remote WinDbg

WinDBG
The WinDBG support for r2 allows you to attach to VM running Windows using a named socket file
(will support more IOs in the future) to debug a windows box using the KD interface over serial port.

Bear in mind that WinDBG support is still work-in-progress, and this is just an initial implementation
which will get better in time.

It is also possible to use the remote GDB interface to connect and debug Windows kernels without
depending on Windows capabilities.

Enable WinDBG support on Windows Vista and higher like this:

bcdedit /debug on
bcdedit /dbgsettings serial debugport:1 baudrate:115200

Starting from Windows 8 there is no way to enforce debugging for every boot, but it is possible to
always show the advanced boot options, which allows to enable kernel debugging:

bcedit /set {globalsettings} advancedoptions true

Or like this for Windows XP: Open boot.ini and add /debug /debugport=COM1 /baudrate=115200:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Debugging with Cable" /fastdetect /debug /d
ebugport=COM1 /baudrate=57600

In case of VMWare

Virtual Machine Settings -> Add -> Serial Port

Device Status:
[v] Connect at power on
Connection:
[v] Use socket (named pipe)
[_/tmp/windbg.pipe________]
From: Server To: Virtual Machine

239
Remote WinDbg

Configure the VirtualBox Machine like this:

Preferences -> Serial Ports -> Port 1

[v] Enable Serial Port

Port Number: [_COM1_______[v]]
Port Mode: [_Host_Pipe__[v]]
[v] Create Pipe
Port/File Path: [_/tmp/windbg.pipe____]

Or just spawn the VM with qemu like this:

$ qemu-system-x86_64 -chardev socket,id=serial0,\

path=/tmp/windbg.pipe,nowait,server \
-serial chardev:serial0 -hda Windows7-VM.vdi

Radare2 will use the 'windbg' io plugin to connect to a socket file created by virtualbox or qemu. Also,
the 'windbg' debugger plugin and we should specify the x86-32 too. (32 and 64 bit debugging is
supported)

$ r2 -a x86 -b 32 -D windbg windbg:///tmp/windbg.pipe

On Windows you should run the following line:

$ radare2 -D windbg windbg://\\.\pipe\com_1

At this point, we will get stuck here:

[0x828997b8]> pd 20
;-- eip:
0x828997b8 cc int3
0x828997b9 c20400 ret 4
0x828997bc cc int3
0x828997bd 90 nop
0x828997be c3 ret
0x828997bf 90 nop

In order to skip that trap we will need to change eip and run 'dc' twice:

240
Remote WinDbg

dr eip=eip+1
dc
dr eip=eip+1
dc

Now the Windows VM will be interactive again. We will need to kill r2 and attach again to get back to
control the kernel.

In addition, the dp command can be used to list all processes, and dpa or dp= to attach to the
process. This will display the base address of the process in the physical memory layout.

241
Command Line Tools

Tools
Radare2 is not just the only tool provided by the radare2 project. The rest if chapters in this book are
focused on explaining the use of the radare2 tool, this chapter will focus on explaining all the other
companion tools that are shipped inside the radare2 project.

All the functionalities provided by the different APIs and plugins have also different tools to allow to
use them from the commandline and integrate them with shellscripts easily.

Thanks to the ortogonal design of the framework it is possible to do all the things that r2 is able from
different places:

these companion tools

native library apis
scripting with r2pipe
the r2 shell

242
Rax2

Rax2
The rax2 utility comes with the radare framework and aims to be a minimalistic expression evaluator
for the shell. It is useful for making base conversions between floating point values, hexadecimal
representations, hexpair strings to ascii, octal to integer. It supports endianness and can be used as a
shell if no arguments are given.

This is the help message of rax2, this tool can be used in the command-line or interactively (reading the
values from stdin), so it can be used as a multi-base calculator.

Inside r2, the functionality of rax2 is available under the ? command. For example:

[0x00000000]> ? 3+4

As you can see, the numeric expressions can contain mathematical expressions like addition,
substraction, .. as well as group operations with parenthesis.

The syntax in which the numbers are represented define the base, for example:

3 : decimal, base 10
0xface : hexadecimal, base 16
0472 : octal, base 8
2M : units, 2 megabytes
...

This is the help message of rax2 -h, which will show you a bunch more syntaxes

243
Rax2

$ rax2 -h
Usage: rax2 [options] [expr ...]
=[base] ; rax2 =10 0x46 -> output in base 10
int -> hex ; rax2 10
hex -> int ; rax2 0xa
-int -> hex ; rax2 -77
-hex -> int ; rax2 0xffffffb3
int -> bin ; rax2 b30
int -> ternary ; rax2 t42
bin -> int ; rax2 1010d
ternary -> int ; rax2 1010dt
float -> hex ; rax2 3.33f
hex -> float ; rax2 Fx40551ed8
oct -> hex ; rax2 35o
hex -> oct ; rax2 Ox12 (O is a letter)
bin -> hex ; rax2 1100011b
hex -> bin ; rax2 Bx63
ternary -> hex ; rax2 212t
hex -> ternary ; rax2 Tx23
raw -> hex ; rax2 -S < /binfile
hex -> raw ; rax2 -s 414141
-l ; append newline to output (for -E/-D/-r/..
-a show ascii table ; rax2 -a
-b bin -> str ; rax2 -b 01000101 01110110
-B str -> bin ; rax2 -B hello
-d force integer ; rax2 -d 3 -> 3 instead of 0x3
-e swap endianness ; rax2 -e 0x33
-D base64 decode ;
-E base64 encode ;
-f floating point ; rax2 -f 6.3+2.1
-F stdin slurp code hex ; rax2 -F < shellcode.[c/py/js]
-h help ; rax2 -h
-i dump as C byte array ; rax2 -i < bytes
-k keep base ; rax2 -k 33+3 -> 36
-K randomart ; rax2 -K 0x34 1020304050
-L bin -> hex(bignum) ; rax2 -L 111111111 # 0x1ff
-n binary number ; rax2 -n 0x1234 # 34120000
-N binary number ; rax2 -N 0x1234 # \x34\x12\x00\x00
-r r2 style output ; rax2 -r 0x1234
-s hexstr -> raw ; rax2 -s 43 4a 50
-S raw -> hexstr ; rax2 -S < /bin/ls > ls.hex
-t tstamp -> str ; rax2 -t 1234567890
-x hash string ; rax2 -x linux osx
-u units ; rax2 -u 389289238 # 317.0M
-w signed word ; rax2 -w 16 0xffff
-v version ; rax2 -v

Some examples:

244
Rax2

$ rax2 3+0x80
0x83

$ rax2 0x80+3
131

$ echo 0x80+3 | rax2

131

$ rax2 -s 4142
AB

$ rax2 -S AB
4142

$ rax2 -S < bin.foo

...

$ rax2 -e 33
0x21000000

$ rax2 -e 0x21000000
33

$ rax2 -K 90203010
+--[0x10302090]---+
|Eo. . |
| . . . . |
| o |
| . |
| S |
| |
| |
| |
| |
+-----------------+

245
Rax2

246
Rafind2

rafind2
Rafind2 is the command line fronted of the r_search library. Which allows you to search for strings,
sequences of bytes with binary masks, etc

$ rafind2 -h
Usage: rafind2 [-mXnzZhqv] [-a align] [-b sz] [-f/t from/to] [-[e|s|S] str] [-x hex] fil
e|dir ..
-a [align] only accept aligned hits
-b [size] set block size
-e [regex] search for regex matches (can be used multiple times)
-f [from] start searching from address 'from'
-h show this help
-i identify filetype (r2 -nqcpm file)
-m magic search, file-type carver
-M [str] set a binary mask to be applied on keywords
-n do not stop on read errors
-r print using radare commands
-s [str] search for a specific string (can be used multiple times)
-S [str] search for a specific wide string (can be used multiple times)
-t [to] stop search at address 'to'
-q quiet - do not show headings (filenames) above matching contents (default fo
r searching a single file)
-v print version and exit
-x [hex] search for hexpair string (909090) (can be used multiple times)
-X show hexdump of search results
-z search for zero-terminated strings
-Z show string found on each search hit

That's how to use it, first we'll search for "lib" inside the /bin/ls binary.

$ rafind2 -s lib /bin/ls

0x5f9
0x675
0x679
...
$

Note that the output is pretty minimal, and shows the offsets where the string lib is found. We can
then use this output to feed other tools.

Counting results:

247
Rafind2

$ rafind2 -s lib /bin/ls | wc -l

Displaying results with context:

$ export F=/bin/ls
$ for a in `rafind2 -s lib $F` ; do \
r2 -ns $a -qc'x 32' $F ; done
0x000005f9 6c69 622f 6479 6c64 .. lib/dyld........
0x00000675 6c69 622f 6c69 6275 .. lib/libutil.dyli
0x00000679 6c69 6275 7469 6c2e .. libutil.dylib...
0x00000683 6c69 6200 000c 0000 .. lib......8......
0x000006a5 6c69 622f 6c69 626e .. lib/libncurses.5
0x000006a9 6c69 626e 6375 7273 .. libncurses.5.4.d
0x000006ba 6c69 6200 0000 0c00 .. lib.......8.....
0x000006dd 6c69 622f 6c69 6253 .. lib/libSystem.B.
0x000006e1 6c69 6253 7973 7465 .. libSystem.B.dyli
0x000006ef 6c69 6200 0000 0000 .. lib......&......

But rafind2 can be also used as a replacement of file to identify the mimetype of a file using the
internal magic database of radare2.

$ rafind2 -i /bin/ls
0x00000000 1 Mach-O

Also works as a strings replacement, similar to what you do with rabin2 -z, but without caring about
parsing headers and obeying binary sections.

$ rafind2 -z /bin/ls| grep http

0x000076e5 %http://www.apple.com/appleca/root.crl0\r
0x00007ae6 https://www.apple.com/appleca/0
0x00007fa9 )http://www.apple.com/certificateauthority0
0x000080ab $http://crl.apple.com/codesigning.crl0

248
Rarun2

Rarun2
Rarun2 is a tool allowing to setup a specified execution environment - redefine stdin/stdout, pipes,
change the environment variables and other settings useful to craft the boundary conditions you need to
run a binary for debugging.

$ rarun2 -h
Usage: rarun2 -v|-t|script.rr2 [directive ..]

It takes the text file in key=value format to specify the execution environment. Rarun2 can be used as
both separate tool or as a part of radare2. To load the rarun2 profile in radare2 you need to use either -
r to load the profile from file or -R to specify the directive from string.

The format of the profile is very simple. Note the most important keys - program and arg*

One of the most common usage cases - redirect the output of debugged program in radare2. For this you
need to use stdio , stdout , stdin , input , and a couple similar keys.

Here is the basic profile example:

249
Rarun2

program=/bin/ls
arg1=/bin
# arg2=hello
# arg3="hello\nworld"
# arg4=:048490184058104849
# arg5=:!ragg2 -p n50 -d 10:0x8048123
# arg6=@arg.txt
# arg7=@300@ABCD # 300 chars filled with ABCD pattern
# system=r2 -
# aslr=no
setenv=FOO=BAR
# unsetenv=FOO
# clearenv=true
# envfile=environ.txt
timeout=3
# timeoutsig=SIGTERM # or 15
# connect=localhost:8080
# listen=8080
# pty=false
# fork=true
# bits=32
# pid=0
# pidfile=/tmp/foo.pid
# #sleep=0
# #maxfd=0
# #execve=false
# #maxproc=0
# #maxstack=0
# #core=false
# #stdio=blah.txt
# #stderr=foo.txt
# stdout=foo.txt
# stdin=input.txt # or !program to redirect input from another program
# input=input.txt
# chdir=/
# chroot=/mnt/chroot
# libpath=$PWD:/tmp/lib
# r2preload=yes
# preload=/lib/libfoo.so
# setuid=2000
# seteuid=2000
# setgid=2001
# setegid=2001
# nice=5

250
Rabin2

Rabin2 — Show Properties of a Binary

Under this bunny-arabic-like name, radare hides a powerful tool to handle binary files, to get
information on imports, sections, headers and other data. Rabin2 can present it in several formats
accepted by other tools, including radare2 itself. Rabin2 understands many file formats: Java CLASS,
ELF, PE, Mach-O or any format supported by plugins, and it is able to obtain symbol import/exports,
library dependencies, strings of data sections, xrefs, entrypoint address, sections, architecture type.

$ rabin2 -h
Usage: rabin2 [-AcdeEghHiIjlLMqrRsSvVxzZ] [-@ at] [-a arch] [-b bits] [-B addr]
[-C F:C:D] [-f str] [-m addr] [-n str] [-N m:M] [-P[-P] pdb]
[-o str] [-O str] [-k query] [-D lang symname] | file
-@ [addr] show section, symbol or import at addr
-A list sub-binaries and their arch-bits pairs
-a [arch] set arch (x86, arm, .. or <arch>_<bits>)
-b [bits] set bits (32, 64 ...)
-B [addr] override base address (pie bins)
-c list classes
-C [fmt:C:D] create [elf,mach0,pe] with Code and Data hexpairs (see -a)
-d show debug/dwarf information
-D lang name demangle symbol name (-D all for bin.demangle=true)
-e entrypoint
-E globally exportable symbols
-f [str] select sub-bin named str
-F [binfmt] force to use that bin plugin (ignore header check)
-g same as -SMZIHVResizcld (show all info)
-G [addr] load address . offset to header
-h this help message
-H header fields
-i imports (symbols imported from libraries)
-I binary info
-j output in json
-k [sdb-query] run sdb query. for example: '*'
-K [algo] calculate checksums (md5, sha1, ..)
-l linked libraries
-L [plugin] list supported bin plugins or plugin details
-m [addr] show source line at addr
-M main (show address of main symbol)
-n [str] show section, symbol or import named str
-N [min:max] force min:max number of chars per string (see -z and -zz)
-o [str] output file/folder for write operations (out by default)
-O [str] write/extract operations (-O help)
-p show physical addresses
-P show debug/pdb information
-PP download pdb file for binary

251
Rabin2

-q be quiet, just show fewer data

-qq show less info (no offset/size for -z for ex.)
-Q show load address used by dlopen (non-aslr libs)
-r radare output
-R relocations
-s symbols
-S sections
-u unfiltered (no rename duplicated symbols/sections)
-v display version and quit
-V Show binary version information
-x extract bins contained in file
-X [fmt] [f] .. package in fat or zip the given files and bins contained in file
-z strings (from data section)
-zz strings (from raw bins [e bin.rawstr=1])
-zzz dump raw strings to stdout (for huge files)
-Z guess size of binary program
......

252
File Identification

File Properties Identification

File type identification is done using -I . With this option, rabin2 prints information on a binary type,
like its encoding, endianness, class, operating system:

$ rabin2 -I /bin/ls
arch x86
binsz 128456
bintype elf
bits 64
canary true
class ELF64
crypto false
endian little
havecode true
intrp /lib64/ld-linux-x86-64.so.2
lang c
linenum false
lsyms false
machine AMD x86-64 architecture
maxopsz 16
minopsz 1
nx true
os linux
pcalign 0
pic true
relocs false
relro partial
rpath NONE
static false
stripped true
subsys linux
va true

To make rabin2 output information in format that the main program, radare2, can understand, pass -
Ir option to it:

253
File Identification

$ rabin2 -Ir /bin/ls

e cfg.bigendian=false
e asm.bits=64
e asm.dwarf=true
e bin.lang=c
e file.type=elf
e asm.os=linux
e asm.arch=x86
e asm.pcalign=0

254
Entrypoint

Code Entrypoints
The -e option passed to rabin2 will show entrypoints for given binary. Two examples:

$ rabin2 -e /bin/ls
[Entrypoints]
vaddr=0x00005310 paddr=0x00005310 baddr=0x00000000 laddr=0x00000000 haddr=0x00000018 typ
e=program

1 entrypoints

$ rabin2 -er /bin/ls

fs symbols
f entry0 1 @ 0x00005310
f entry0_haddr 1 @ 0x00000018
s entry0

255
Imports

Imports
Rabin2 is able to find imported objects by an executable, as well as their offsets in its PLT. This
information is useful, for example, to understand what external function is invoked by call

instruction. Pass -i flag to rabin2 to get a list of imports. An example:

$ rabin2 -i /bin/ls
[Imports]
1 0x000032e0 GLOBAL FUNC __ctype_toupper_loc
2 0x000032f0 GLOBAL FUNC getenv
3 0x00003300 GLOBAL FUNC sigprocmask
4 0x00003310 GLOBAL FUNC __snprintf_chk
5 0x00003320 GLOBAL FUNC raise
6 0x00000000 GLOBAL FUNC free
7 0x00003330 GLOBAL FUNC abort
8 0x00003340 GLOBAL FUNC __errno_location
9 0x00003350 GLOBAL FUNC strncmp
10 0x00000000 WEAK NOTYPE _ITM_deregisterTMCloneTable
11 0x00003360 GLOBAL FUNC localtime_r
12 0x00003370 GLOBAL FUNC _exit
13 0x00003380 GLOBAL FUNC strcpy
14 0x00003390 GLOBAL FUNC __fpending
15 0x000033a0 GLOBAL FUNC isatty
16 0x000033b0 GLOBAL FUNC sigaction
17 0x000033c0 GLOBAL FUNC iswcntrl
18 0x000033d0 GLOBAL FUNC wcswidth
19 0x000033e0 GLOBAL FUNC localeconv
20 0x000033f0 GLOBAL FUNC mbstowcs
21 0x00003400 GLOBAL FUNC readlink
...

256
Exports

Exports
Rabin2 is able to find exports. For example:

$ rabin2 -E /usr/lib/libr_bin.so | head

[Exports]
210 0x000ae1f0 0x000ae1f0 GLOBAL FUNC 200 r_bin_java_print_exceptions_attr_summary
211 0x000afc90 0x000afc90 GLOBAL FUNC 135 r_bin_java_get_args
212 0x000b18e0 0x000b18e0 GLOBAL FUNC 35 r_bin_java_get_item_desc_from_bin_cp_list
213 0x00022d90 0x00022d90 GLOBAL FUNC 204 r_bin_class_add_method
214 0x000ae600 0x000ae600 GLOBAL FUNC 175 r_bin_java_print_fieldref_cp_summary
215 0x000ad880 0x000ad880 GLOBAL FUNC 144 r_bin_java_print_constant_value_attr_summar
y
216 0x000b7330 0x000b7330 GLOBAL FUNC 679 r_bin_java_print_element_value_summary
217 0x000af170 0x000af170 GLOBAL FUNC 65 r_bin_java_create_method_fq_str
218 0x00079b00 0x00079b00 GLOBAL FUNC 15 LZ4_createStreamDecode

257
Symbols (exports)

Symbols (Exports)
With rabin2, the generated symbols list format is similar to the imports list. Use the -s option to get it:

rabin2 -s /bin/ls | head

[Symbols]
110 0x000150a0 0x000150a0 GLOBAL FUNC 56 _obstack_allocated_p
111 0x0001f600 0x0021f600 GLOBAL OBJ 8 program_name
112 0x0001f620 0x0021f620 GLOBAL OBJ 8 stderr
113 0x00014f90 0x00014f90 GLOBAL FUNC 21 _obstack_begin_1
114 0x0001f600 0x0021f600 WEAK OBJ 8 program_invocation_name
115 0x0001f5c0 0x0021f5c0 GLOBAL OBJ 8 alloc_failed_handler
116 0x0001f5f8 0x0021f5f8 GLOBAL OBJ 8 optarg
117 0x0001f5e8 0x0021f5e8 GLOBAL OBJ 8 stdout
118 0x0001f5e0 0x0021f5e0 GLOBAL OBJ 8 program_short_name

With the -sr option rabin2 produces a radare2 script instead. It can later be passed to the core to
automatically flag all symbols and to define corresponding byte ranges as functions and data blocks.

$ rabin2 -sr /bin/ls | head

fs symbols
f sym.obstack_allocated_p 56 0x000150a0
f sym.program_invocation_name 8 0x0021f600
f sym.stderr 8 0x0021f620
f sym.obstack_begin_1 21 0x00014f90
f sym.program_invocation_name 8 0x0021f600
f sym.obstack_alloc_failed_handler 8 0x0021f5c0
f sym.optarg 8 0x0021f5f8
f sym.stdout 8 0x0021f5e8
f sym.program_invocation_short_name 8 0x0021f5e0

258
Libraries

List Libraries
Rabin2 can list libraries used by a binary with the -l option:

$ rabin2 -l `which r2`

[Linked libraries]
libr_core.so
libr_parse.so
libr_search.so
libr_cons.so
libr_config.so
libr_bin.so
libr_debug.so
libr_anal.so
libr_reg.so
libr_bp.so
libr_io.so
libr_fs.so
libr_asm.so
libr_syscall.so
libr_hash.so
libr_magic.so
libr_flag.so
libr_egg.so
libr_crypto.so
libr_util.so
libpthread.so.0
libc.so.6

22 libraries

Lets check the output with ldd command:

259
Libraries

$ ldd `which r2`

linux-vdso.so.1 (0x00007fffba38e000)
libr_core.so => /usr/lib64/libr_core.so (0x00007f94b4678000)
libr_parse.so => /usr/lib64/libr_parse.so (0x00007f94b4425000)
libr_search.so => /usr/lib64/libr_search.so (0x00007f94b421f000)
libr_cons.so => /usr/lib64/libr_cons.so (0x00007f94b4000000)
libr_config.so => /usr/lib64/libr_config.so (0x00007f94b3dfa000)
libr_bin.so => /usr/lib64/libr_bin.so (0x00007f94b3afd000)
libr_debug.so => /usr/lib64/libr_debug.so (0x00007f94b38d2000)
libr_anal.so => /usr/lib64/libr_anal.so (0x00007f94b2fbd000)
libr_reg.so => /usr/lib64/libr_reg.so (0x00007f94b2db4000)
libr_bp.so => /usr/lib64/libr_bp.so (0x00007f94b2baf000)
libr_io.so => /usr/lib64/libr_io.so (0x00007f94b2944000)
libr_fs.so => /usr/lib64/libr_fs.so (0x00007f94b270e000)
libr_asm.so => /usr/lib64/libr_asm.so (0x00007f94b1c69000)
libr_syscall.so => /usr/lib64/libr_syscall.so (0x00007f94b1a63000)
libr_hash.so => /usr/lib64/libr_hash.so (0x00007f94b185a000)
libr_magic.so => /usr/lib64/libr_magic.so (0x00007f94b164d000)
libr_flag.so => /usr/lib64/libr_flag.so (0x00007f94b1446000)
libr_egg.so => /usr/lib64/libr_egg.so (0x00007f94b1236000)
libr_crypto.so => /usr/lib64/libr_crypto.so (0x00007f94b1016000)
libr_util.so => /usr/lib64/libr_util.so (0x00007f94b0d35000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f94b0b15000)
libc.so.6 => /lib64/libc.so.6 (0x00007f94b074d000)
libr_lang.so => /usr/lib64/libr_lang.so (0x00007f94b0546000)
libr_socket.so => /usr/lib64/libr_socket.so (0x00007f94b0339000)
libm.so.6 => /lib64/libm.so.6 (0x00007f94affaf000)
libdl.so.2 => /lib64/libdl.so.2 (0x00007f94afdab000)
/lib64/ld-linux-x86-64.so.2 (0x00007f94b4c79000)
libssl.so.1.0.0 => /usr/lib64/libssl.so.1.0.0 (0x00007f94afb3c000)
libcrypto.so.1.0.0 => /usr/lib64/libcrypto.so.1.0.0 (0x00007f94af702000)
libutil.so.1 => /lib64/libutil.so.1 (0x00007f94af4ff000)
libz.so.1 => /lib64/libz.so.1 (0x00007f94af2e8000)

If you compare the outputs of rabin2 -l and ldd , you will notice that rabin2 lists fewer libraries
than ldd . The reason is that rabin2 does not follow and does not show dependencies of libraries. Only
direct binary dependencies are shown.

260
Strings

Strings
The -z option is used to list readable strings found in the .rodata section of ELF binaries, or the .text
section of PE files. Example:

$ rabin2 -z /bin/ls | head

000 0x000160f8 0x000160f8 11 12 (.rodata) ascii dev_ino_pop
001 0x00016188 0x00016188 10 11 (.rodata) ascii sort_files
002 0x00016193 0x00016193 6 7 (.rodata) ascii posix-
003 0x0001619a 0x0001619a 4 5 (.rodata) ascii main
004 0x00016250 0x00016250 10 11 (.rodata) ascii ?pcdb-lswd
005 0x00016260 0x00016260 65 66 (.rodata) ascii # Configuration file for dircolors, a
utility to help you set the
006 0x000162a2 0x000162a2 72 73 (.rodata) ascii # LS_COLORS environment variable used
by GNU ls with the --color option.
007 0x000162eb 0x000162eb 56 57 (.rodata) ascii # Copyright (C) 1996-2018 Free Softwar
e Foundation, Inc.
008 0x00016324 0x00016324 70 71 (.rodata) ascii # Copying and distribution of this fil
e, with or without modification,
009 0x0001636b 0x0001636b 76 77 (.rodata) ascii # are permitted provided the copyright
notice and this notice are preserved.

With the -zr option, this information is represented as a radare2 commands list. It can be used in a
radare2 session to automatically create a flag space called "strings" pre-populated with flags for all
strings found by rabin2. Furthermore, this script will mark corresponding byte ranges as strings instead
of code.

$ rabin2 -zr /bin/ls | head

fs stringsf str.dev_ino_pop 12 @ 0x000160f8
Cs 12 @ 0x000160f8
f str.sort_files 11 @ 0x00016188
Cs 11 @ 0x00016188
f str.posix 7 @ 0x00016193
Cs 7 @ 0x00016193
f str.main 5 @ 0x0001619a
Cs 5 @ 0x0001619a
f str.pcdb_lswd 11 @ 0x00016250
Cs 11 @ 0x00016250

261
Program Sections

Program Sections
Rabin2 called with the -S option gives complete information about the sections of an executable. For
each section the index, offset, size, alignment, type and permissions, are shown. The next example
demonstrates this:

$ rabin2 -S /bin/ls
[Sections]
00 0x00000000 0 0x00000000 0 ----
01 0x00000238 28 0x00000238 28 -r-- .interp
02 0x00000254 32 0x00000254 32 -r-- .note.ABI_tag
03 0x00000278 176 0x00000278 176 -r-- .gnu.hash
04 0x00000328 3000 0x00000328 3000 -r-- .dynsym
05 0x00000ee0 1412 0x00000ee0 1412 -r-- .dynstr
06 0x00001464 250 0x00001464 250 -r-- .gnu.version
07 0x00001560 112 0x00001560 112 -r-- .gnu.version_r
08 0x000015d0 4944 0x000015d0 4944 -r-- .rela.dyn
09 0x00002920 2448 0x00002920 2448 -r-- .rela.plt
10 0x000032b0 23 0x000032b0 23 -r-x .init
11 0x000032d0 1648 0x000032d0 1648 -r-x .plt
12 0x00003940 24 0x00003940 24 -r-x .plt.got
13 0x00003960 73931 0x00003960 73931 -r-x .text
14 0x00015a2c 9 0x00015a2c 9 -r-x .fini
15 0x00015a40 20201 0x00015a40 20201 -r-- .rodata
16 0x0001a92c 2164 0x0001a92c 2164 -r-- .eh_frame_hdr
17 0x0001b1a0 11384 0x0001b1a0 11384 -r-- .eh_frame
18 0x0001e390 8 0x0021e390 8 -rw- .init_array
19 0x0001e398 8 0x0021e398 8 -rw- .fini_array
20 0x0001e3a0 2616 0x0021e3a0 2616 -rw- .data.rel.ro
21 0x0001edd8 480 0x0021edd8 480 -rw- .dynamic
22 0x0001efb8 56 0x0021efb8 56 -rw- .got
23 0x0001f000 840 0x0021f000 840 -rw- .got.plt
24 0x0001f360 616 0x0021f360 616 -rw- .data
25 0x0001f5c8 0 0x0021f5e0 4824 -rw- .bss
26 0x0001f5c8 232 0x00000000 232 ---- .shstrtab

With the -Sr option, rabin2 will flag the start/end of every section, and will pass the rest of
information as a comment.

262
Program Sections

$ rabin2 -Sr /bin/ls | head

fs sections
S 0x00000000 0x00000000 0x00000000 0x00000000 0
f section. 0 0x00000000
f section_end. 1 0x00000000
CC section 0 va=0x00000000 pa=0x00000000 sz=0 vsz=0 rwx=---- @ 0x00000000
S 0x00000238 0x00000238 0x0000001c 0x0000001c .interp 4
f section..interp 28 0x00000238
f section_end..interp 1 0x00000254
CC section 1 va=0x00000238 pa=0x00000238 sz=28 vsz=28 rwx=-r-- .interp @ 0x00000238
S 0x00000254 0x00000254 0x00000020 0x00000020 .note.ABI_tag 4

263
Radiff2

Radiff2
Radiff2 is a tool designed to compare binary files, similar to how regular diff compares text files.

$ radiff2 -h
Usage: radiff2 [-abBcCdjrspOxuUvV] [-A[A]] [-g sym] [-t %] [file] [file]
-a [arch] specify architecture plugin to use (x86, arm, ..)
-A [-A] run aaa or aaaa after loading each binary (see -C)
-b [bits] specify register size for arch (16 (thumb), 32, 64, ..)
-B output in binary diff (GDIFF)
-c count of changes
-C graphdiff code (columns: off-A, match-ratio, off-B) (see -A)
-d use delta diffing
-D show disasm instead of hexpairs
-e [k=v] set eval config var value for all RCore instances
-g [sym|off1,off2] graph diff of given symbol, or between two offsets
-G [cmd] run an r2 command on every RCore instance created
-i diff imports of target files (see -u, -U and -z)
-j output in json format
-n print bare addresses only (diff.bare=1)
-O code diffing with opcode bytes only
-p use physical addressing (io.va=0)
-q quiet mode (disable colors, reduce output)
-r output in radare commands
-s compute edit distance (no substitution, Eugene W. Myers' O(ND) diff algorit
hm)
-ss compute Levenshtein edit distance (substitution is allowed, O(N^2))
-S [name] sort code diff (name, namelen, addr, size, type, dist) (only for -C or -g)
-t [0-100] set threshold for code diff (default is 70%)
-x show two column hexdump diffing
-u unified output (---+++)
-U unified output using system 'diff'
-v show version information
-V be verbose (current only for -s)
-z diff on extracted strings

264
Binary Diffing

Binary Diffing
This section is based on the http://radare.today article "binary diffing"

Without any parameters, radiff2 by default shows what bytes are changed and their corresponding
offsets:

$ radiff2 genuine cracked

0x000081e0 85c00f94c0 => 9090909090 0x000081e0
0x0007c805 85c00f84c0 => 9090909090 0x0007c805

$ rasm2 -d 85c00f94c0
test eax, eax
sete al

Notice how the two jumps are nop'ed.

For bulk processing, you may want to have a higher-level overview of differences. This is why radare2
is able to compute the distance and the percentage of similarity between two files with the -s option:

$ radiff2 -s /bin/true /bin/false

similarity: 0.97
distance: 743

If you want more concrete data, it's also possible to count the differences, with the -c option:

$ radiff2 -c genuine cracked

If you are unsure whether you are dealing with similar binaries, with -C flag you can check there are
matching functions. It this mode, it will give you three columns for all functions: "First file offset",
"Percentage of matching" and "Second file offset".

265
Binary Diffing

$ radiff2 -C /bin/false /bin/true

Moreover, we can ask radiff2 to perform analysis first - adding -A option will run aaa on the
binaries. And we can specify binaries architecture for this analysis too using

$ radiff2 -AC -a x86 /bin/true /bin/false | grep UNMATCH

[x] Analyze all flags starting with sym. and entry0 (aa)
[x] Analyze len bytes of instructions for references (aar)
[x] Analyze function calls (aac)
[ ] [*] Use -AA or aaaa to perform additional experimental analysis.
[x] Constructing a function name for fcn.* and sym.func.* functions (aan))
[x] Analyze all flags starting with sym. and entry0 (aa)
[x] Analyze len bytes of instructions for references (aar)
[x] Analyze function calls (aac)
[ ] [*] Use -AA or aaaa to perform additional experimental analysis.
[x] Constructing a function name for fcn.* and sym.func.* functions (aan))
sub.fileno_500 86 0x4500 | UNMATCH (0.965116) | 0x4510 86
sub.fileno_510
sub.__freading_4c0 59 0x44c0 | UNMATCH (0.949153) | 0x44d0 59
sub.__freading_4d0
sub.fileno_440 120 0x4440 | UNMATCH (0.200000) | 0x4450 120
sub.fileno_450
sub.setlocale_fa0 64 0x3fa0 | UNMATCH (0.104651) | 0x3fb0 64
sub.setlocale_fb0
fcn.00003a50 120 0x3a50 | UNMATCH (0.125000) | 0x3a60 120
fcn.00003a60

And now a cool feature : radare2 supports graph-diffing, à la DarunGrim, with the -g option. You can
either give it a symbol name, of specify two offsets, if the function you want to diff is named differently
in compared files. For example, radiff2 -g main /bin/true /bin/false | xdot - will show
differences in main() function of Unix true and false programs. You can compare it to radiff2
-g main /bin/false /bin/true (Notice the order of the arguments) to get the two versions. This is the

result:

266
Binary Diffing

Parts in yellow indicate that some offsets do not match. The grey piece means a perfect match. The red
one highlights a strong difference. If you look closely, you will see that the left part of the picture has
mov edi, 0x1; call sym.imp.exit , while the right one has xor edi, edi; call sym.imp.exit .

Binary diffing is an important feature for reverse engineering. It can be used to analyze security updates,
infected binaries, firmware changes and more...

We have only shown the code analysis diffing functionality, but radare2 supports additional types of
diffing between two binaries: at byte level, deltified similarities, and more to come.

We have plans to implement more kinds of bindiffing algorithms into r2, and why not, add support for
ASCII art graph diffing and better integration with the rest of the toolkit.

267
Rasm2

Rasm2
rasm2 is an inline assembler/disassembler. Initially, rasm tool was designed to be used for binary

patching. Its main function is to get bytes corresponding to given machine instruction opcode.

$ rasm2 -h
Usage: rasm2 [-ACdDehLBvw] [-a arch] [-b bits] [-o addr] [-s syntax]
[-f file] [-F fil:ter] [-i skip] [-l len] 'code'|hex|-
-a [arch] Set architecture to assemble/disassemble (see -L)
-A Show Analysis information from given hexpairs
-b [bits] Set cpu register size (8, 16, 32, 64) (RASM2_BITS)
-B Binary input/output (-l is mandatory for binary input)
-c [cpu] Select specific CPU (depends on arch)
-C Output in C format
-d, -D Disassemble from hexpair bytes (-D show hexpairs)
-e Use big endian instead of little endian
-E Display ESIL expression (same input as in -d)
-f [file] Read data from file
-F [in:out] Specify input and/or output filters (att2intel, x86.pseudo, ...)
-h, -hh Show this help, -hh for long
-i [len] ignore/skip N bytes of the input buffer
-j output in json format
-k [kernel] Select operating system (linux, windows, darwin, ..)
-l [len] Input/Output length
-L List Asm plugins: (a=asm, d=disasm, A=analyze, e=ESIL)
-o [offset] Set start address for code (default 0)
-O [file] Output file name (rasm2 -Bf a.asm -O a)
-p Run SPP over input for assembly
-q quiet mode
-r output in radare commands
-s [syntax] Select syntax (intel, att)
-v Show version information
-w What's this instruction for? describe opcode
If '-l' value is greater than output length, output is padded with nops
If the last argument is '-' reads from stdin
Environment:
RASM2_NOPLUGINS do not load shared plugins (speedup loading)
RASM2_ARCH same as rasm2 -a
RASM2_BITS same as rasm2 -b
R_DEBUG if defined, show error messages and crash signal

Plugins for supported target architectures can be listed with the -L option. Knowing a plugin name,
you can use it by specifying its name to the -a option

268
Rasm2

$ rasm2 -L
_dAe 8 16 6502 LGPL3 6502/NES/C64/Tamagotchi/T-1000 CPU
_dAe 8 8051 PD 8051 Intel CPU
_dA_ 16 32 arc GPL3 Argonaut RISC Core
a___ 16 32 64 arm.as LGPL3 as ARM Assembler (use ARM_AS environment)
adAe 16 32 64 arm BSD Capstone ARM disassembler
_dA_ 16 32 64 arm.gnu GPL3 Acorn RISC Machine CPU
_d__ 16 32 arm.winedbg LGPL2 WineDBG's ARM disassembler
adAe 8 16 avr GPL AVR Atmel
adAe 16 32 64 bf LGPL3 Brainfuck (by pancake, nibble) v4.0.0
_dA_ 32 chip8 LGPL3 Chip8 disassembler
_dA_ 16 cr16 LGPL3 cr16 disassembly plugin
_dA_ 32 cris GPL3 Axis Communications 32-bit embedded processor
adA_ 32 64 dalvik LGPL3 AndroidVM Dalvik
ad__ 16 dcpu16 PD Mojang's DCPU-16
_dA_ 32 64 ebc LGPL3 EFI Bytecode
adAe 16 gb LGPL3 GameBoy(TM) (z80-like)
_dAe 16 h8300 LGPL3 H8/300 disassembly plugin
_dAe 32 hexagon LGPL3 Qualcomm Hexagon (QDSP6) V6
_d__ 32 hppa GPL3 HP PA-RISC
_dAe i4004 LGPL3 Intel 4004 microprocessor
_dA_ 8 i8080 BSD Intel 8080 CPU
adA_ 32 java Apache Java bytecode
_d__ 32 lanai GPL3 LANAI
_d__ 8 lh5801 LGPL3 SHARP LH5801 disassembler
_d__ 32 lm32 BSD disassembly plugin for Lattice Micro 32 ISA
_dA_ 16 32 m68k BSD Capstone M68K disassembler
_dA_ 32 malbolge LGPL3 Malbolge Ternary VM
_d__ 16 mcs96 LGPL3 condrets car
adAe 16 32 64 mips BSD Capstone MIPS disassembler
adAe 32 64 mips.gnu GPL3 MIPS CPU
_dA_ 16 msp430 LGPL3 msp430 disassembly plugin
_dA_ 32 nios2 GPL3 NIOS II Embedded Processor
_dAe 8 pic LGPL3 PIC disassembler
_dAe 32 64 ppc BSD Capstone PowerPC disassembler
_dA_ 32 64 ppc.gnu GPL3 PowerPC
_d__ 32 propeller LGPL3 propeller disassembly plugin
_dA_ 32 64 riscv GPL RISC-V
_dAe 32 rsp LGPL3 Reality Signal Processor
_dAe 32 sh GPL3 SuperH-4 CPU
_dA_ 8 16 snes LGPL3 SuperNES CPU
_dAe 32 64 sparc BSD Capstone SPARC disassembler
_dA_ 32 64 sparc.gnu GPL3 Scalable Processor Architecture
_d__ 16 spc700 LGPL3 spc700, snes' sound-chip
_d__ 32 sysz BSD SystemZ CPU disassembler
_dA_ 32 tms320 LGPLv3 TMS320 DSP family (c54x,c55x,c55x+,c64x)
_d__ 32 tricore GPL3 Siemens TriCore CPU
_dAe 32 v810 LGPL3 v810 disassembly plugin
_dAe 32 v850 LGPL3 v850 disassembly plugin
_dAe 8 32 vax GPL VAX

269
Rasm2

adA_ 32 wasm MIT WebAssembly (by cgvwzq) v0.1.0

_dA_ 32 ws LGPL3 Whitespace esotheric VM
a___ 16 32 64 x86.as LGPL3 Intel X86 GNU Assembler
_dAe 16 32 64 x86 BSD Capstone X86 disassembler
a___ 16 32 64 x86.nasm LGPL3 X86 nasm assembler
a___ 16 32 64 x86.nz LGPL3 x86 handmade assembler
_dA_ 16 xap PD XAP4 RISC (CSR)
_dA_ 32 xcore BSD Capstone XCore disassembler
_dAe 32 xtensa GPL3 XTensa CPU
adA_ 8 z80 GPL Zilog Z80

Note that "ad" in the first column means both assembler and disassembler are offered by a
corresponding plugin. "d" indicates disassembler, "a" means only assembler is available.

270
Assemble

Assembler
Assembling is the action to take a computer instruction in human readable form (using mnemonics) and
convert that into a bunch of bytes that can be executed by a machine.

In radare2, the assembler and disassembler logic is implemented in the rasm* API, and can be used with
the pa and pad commands from the commandline as well as using rasm2 .

Rasm2 can be used to quickly copy-paste hexpairs that represent a given machine instruction. The
following line is assembling this mov instruction for x86/32.

$ rasm2 -a x86 -b 32 'mov eax, 33'

b821000000

Apart from the specifying the input as an argument, you can also pipe it to rasm2:

$ echo 'push eax;nop;nop' | rasm2 -f -

5090

As you have seen, rasm2 can assemble one or many instructions. In line by separating them with a
semicolon ; , but can also read that from a file, using generic nasm/gas/.. syntax and directives. You
can check the rasm2 manpage for more details on this.

The pa and pad are a subcommands of print, what means they will only print assembly or
disassembly. In case you want to actually write the instruction it is required to use wa or wx
commands with the assembly string or bytes appended.

The assembler understands the following input languages and their flavors: x86 (Intel and AT&T
variants), olly (OllyDBG syntax), powerpc (PowerPC), arm and java . For Intel syntax, rasm2
tries to mimic NASM or GAS.

There are several examples in the rasm2 source code directory. Consult them to understand how you can
assemble a raw binary file from a rasm2 description.

Lets create an assembly file called selfstop.rasm :

271
Assemble

;
; Self-Stop shellcode written in rasm for x86
;
; --pancake
;

.arch x86
.equ base 0x8048000
.org 0x8048000 ; the offset where we inject the 5 byte jmp

selfstop:
push 0x8048000
pusha
mov eax, 20
int 0x80

mov ebx, eax

mov ecx, 19
mov eax, 37
int 0x80
popa
ret
;
; The call injection
;

ret

Now we can assemble it in place:

[0x00000000]> e asm.bits = 32
[0x00000000]> wx `!rasm2 -f a.rasm`
[0x00000000]> pd 20
0x00000000 6800800408 push 0x8048000 ; 0x08048000
0x00000005 60 pushad
0x00000006 b814000000 mov eax, 0x14 ; 0x00000014
0x0000000b cd80 int 0x80
syscall[0x80][0]=?
0x0000000d 89c3 mov ebx, eax
0x0000000f b913000000 mov ecx, 0x13 ; 0x00000013
0x00000014 b825000000 mov eax, 0x25 ; 0x00000025
0x00000019 cd80 int 0x80
syscall[0x80][0]=?
0x0000001b 61 popad
0x0000001c c3 ret
0x0000001d c3 ret

272
Assemble

Visual mode
Assembling also is accessible in radare2 visual mode through pressing A key to insert the assembly in
the current offset.

The cool thing of writing assembly using the visual assembler interface that the changes are done in
memory until you press enter.

So you can check the size of the code and which instructions is overlapping before commiting the
changes.

273
Disassemble

Disassembler
Disassembling is the inverse action of assembling. Rasm2 takes hexpair as an input (but can also take a
file in binary form) and show the human readable form.

To do this we can use the -d option of rasm2 like this:

$ rasm2 -a x86 -b 32 -d '90'

nop

Rasm2 also have the -D flag to show the disassembly like -d does, but includes offset and bytes.

In radare2 there are many commands to perform a disassembly from a specific place in memory.

You might be interested in trying if you want different outputs for later parsing with your scripts, or just
grep to find what you are looking for:

pd N
Disassemble N instructions

pD N
Disassemble N bytes

pda
Disassemble all instructions (seeking 1 byte, or the minimum alignment instruction size), which can be
useful for ROP

pi, pI
Same as pd and pD , but using a simpler output.

274
Configuration

Disassembler Configuration
The assembler and disassembler have many small switches to tweak the output.

Those configurations are available through the e command. Here there are the most common ones:

asm.bytes - show/hide bytes

asm.offset - show/hide offset
asm.lines - show/hide lines
asm.ucase - show disasm in uppercase
...

Use the e??asm. for more details.

275
Ragg2

ragg2
ragg2 stands for radare2 egg , this is the basic block to construct relocatable snippets of code to be
used for injection in target processes when doing exploiting.

ragg2 compiles programs written in a simple high-level language into tiny binaries for x86, x86-64, and
ARM.

By default it will compile it's own ragg2 language, but you can also compile C code using GCC or
Clang shellcodes depending on the file extension. Lets create C file called a.c :

int main() {
write(1, "Hello World\n", 13);
return 0;
}

$ ragg2 -a x86 -b32 a.c

e900000000488d3516000000bf01000000b80400000248c7c20d0000000f0531c0c348656c6c6f20576f726c
640a00

$ rasm2 -a x86 -b 32 -D e900000000488d3516000000bf01000000b80400000248c7c20d0000000f0531

c0c348656c6c6f20576f726c640a00
0x00000000 5 e900000000 jmp 5
0x00000005 1 48 dec eax
0x00000006 6 8d3516000000 lea esi, [0x16]
0x0000000c 5 bf01000000 mov edi, 1
0x00000011 5 b804000002 mov eax, 0x2000004
0x00000016 1 48 dec eax
0x00000017 6 c7c20d000000 mov edx, 0xd
0x0000001d 2 0f05 syscall
0x0000001f 2 31c0 xor eax, eax
0x00000021 1 c3 ret
0x00000022 1 48 dec eax
0x00000023 2 656c insb byte es:[edi], dx
0x00000025 1 6c insb byte es:[edi], dx
0x00000026 1 6f outsd dx, dword [esi]
0x00000027 3 20576f and byte [edi + 0x6f], dl
0x0000002a 2 726c jb 0x98
0x0000002c 3 640a00 or al, byte fs:[eax]

Compiling ragg2 example

276
Ragg2

$ cat hello.r
exit@syscall(1);

main@global() {
exit(2);
}

$ ragg2 -a x86 -b 64 hello.r

48c7c00200000050488b3c2448c7c0010000000f054883c408c3
0x00000000 1 48 dec eax
0x00000001 6 c7c002000000 mov eax, 2
0x00000007 1 50 push eax
0x00000008 1 48 dec eax
0x00000009 3 8b3c24 mov edi, dword [esp]
0x0000000c 1 48 dec eax
0x0000000d 6 c7c001000000 mov eax, 1
0x00000013 2 0f05 syscall
0x00000015 1 48 dec eax
0x00000016 3 83c408 add esp, 8
0x00000019 1 c3 ret

$ rasm2 -a x86 -b 64 -D 48c7c00200000050488b3c2448c7c0010000000f054883c408c3

0x00000000 7 48c7c002000000 mov rax, 2
0x00000007 1 50 push rax
0x00000008 4 488b3c24 mov rdi, qword [rsp]
0x0000000c 7 48c7c001000000 mov rax, 1
0x00000013 2 0f05 syscall
0x00000015 4 4883c408 add rsp, 8
0x00000019 1 c3 ret

Tiny binaries
You can create them using the -F flag in ragg2, or the -C in rabin2.

277
Language

Syntax of the language

The code of r_egg is compiled as in a flow. It is a one-pass compiler;

this means that you have to define the proper stackframe size at the

beginning of the function, and you have to define the functions in

order to avoid getting compilation errors.

The compiler generates assembly code for x86-{32,64} and arm. But it aims

to support more platforms. This code is the compiled with r_asm and

injected into a tiny binary with r_bin.

independent raw eggs to be injected on running processes or to patch

on-disk binaries.

The generated code is not yet optimized, but it's safe to be executed

at any place in the code.

Preprocessor
Aliases
Sometimes you just need to replace at compile time a single entity on

multiple places. Aliases are translated into 'equ' statements in assembly

language. This is just an assembler-level keyword redefinition.

AF_INET@alias(2);

printf@alias(0x8053940);

Includes
Use cat(1) or the preprocessor to concatenate multiple files to be compiled.
278
Language

INCDIR@alias("/usr/include/ragg2");

sys-osx.r@include(INCDIR);

Hashbang
eggs can use a hashbang to make them executable.

$ head -n1 hello.r

#!/usr/bin/ragg2 -X

$ ./hello.r

Hello World!

Main
The execution of the code is done as in a flow. The first function to be

defined will be the first one to be executed. If you want to run main()

just do like this:

#!/usr/bin/ragg2 -X

main();

...

main@global(128,64) {

...

Function definition
You may like to split up your code into several code blocks. Those blocks

are bound to a label followed by root brackets '{ ... }'

Function signatures
name@type(stackframesize,staticframesize) { body }

name : name of the function to define

type : see function types below

stackframesize : get space from stack to store local variables

279
Language

staticframesize : get space from stack to store static variables (strings)

body : code of the function

Function types
alias Used to create aliases

data ; the body of the block is defined in .data

inline ; the function body is inlined when called

global ; make the symbol global

fastcall ; function that is called using the fast calling convention

syscall ; define syscall calling convention signature

Syscalls
r_egg offers a syntax sugar for defining syscalls. The syntax is like this:
exit@syscall(1);

@syscall() {

` : mov eax, .arg```

: int 0x80

main@global() {

exit (0);

Libraries
At the moment there is no support for linking r_egg programs to system

libraries. but if you inject the code into a program (disk/memory) you

can define the address of each function using the @alias syntax.

Core library
280
Language

There's a work-in-progress libc-like library written completely in r_egg

Variables
.arg

.arg0

.arg1

.arg2

.var0

.var2

.fix

.ret ; eax for x86, r0 for arm

.bp

.pc

.sp

Attention: All the numbers after .var and .arg mean the offset with the

top of stack, not variable symbols.

Arrays
Supported as raw pointers. TODO: enhance this feature

Tracing
Sometimes r_egg programs will break or just not work as expected. Use the

'trace' architecture to get a arch-backend call trace:

$ ragg2 -a trace -s yourprogram.r

Pointers
TODO: Theorically '*' is used to get contents of a memory pointer.

Virtual registers

281
Language

TODO: a0, a1, a2, a3, sp, fp, bp, pc

Math operations
Ragg2 supports local variables assignment by math operating, including

the following operators:

+ - * / & | ^

Return values
The return value is stored in the a0 register, this register is set when

calling a function or when typing a variable name without assignment.

$ cat test.r
add@global(4) {
.var0 = .arg0 + .arg1;
.var0;
}

main@global() {
add (3,4);
}

$ ragg2 -F -o test test.r

$ ./test
$ echo $?
7

Traps
Each architecture have a different instruction to break the execution of

the program. REgg language captures calls to 'break()' to run the emit_trap

callback of the selected arch. The

break() ; --> compiles into 'int3' on x86

break; --> compiles into 'int3' on x86

Inline assembly
282
Language

Lines prefixed with ':' char are just inlined in the output assembly.

: jmp 0x8048400

: .byte 33,44

Labels
You can define labels using the : keyword like this:

:label_name:

/* loop forever */

goto(label_name )

Control flow
goto (addr) -- branch execution

while (cond)

if (cond)

if (cond) { body } else { body }

break () -- executes a trap instruction

Comments
Supported syntax for comments are:

/* multiline comment */'

// single line comment

# single line comment

283
Rahash2

rahash2
The rahash2 tool can be used to compute checksums of files, disk devices or strings. By block or
entirely using many different hash algorithms.

This tool is also capable of doing some encoding/decoding operations like base64 and xor encryption.

This is an example usage:

$ rahash2 -a md5 -s "hello world"

Note that rahash2 also permits to read from stdin in a stream, so you don't need 4GB of ram to compute
the hash of a 4GB file.

Hashing by blocks
When doing forensics, it is useful to compute partial checksums. The reason for that is because you may
want to split a huge file into small portions that are easier to identify by contents or regions in the disk.

This will spot the same hash for blocks containing the same contents. For example, if filled by zeros.

But also, it can be used to find which blocks have changed between more than one sample dump.

This can be useful when analyzing ram dumps from a virtual machine for example. Use this command
for this:

$ rahash2 -B 1M -b -a sha256 /bin/ls

Hashing with rabin2

The rabin2 tool parses the binary headers of the files, but it also have the ability to use the rhash plugins
to compute checksum of sections in the binary.

$ rabin2 -K md5 -S /bin/ls

284
Rahash2

Obtaining hashes within radare2 session

To calculate a checksum of current block when running radare2, use the ph command. Pass an
algorithm name to it as a parameter. An example session:

$ radare2 /bin/ls
[0x08049790]> bf entry0
[0x08049790]> ph md5
d2994c75adaa58392f953a448de5fba7

You can use all hashing algorithms supported by rahash2 :

285
Rahash2

[0x00000000]> ph?
md5
sha1
sha256
sha384
sha512
md4
xor
xorpair
parity
entropy
hamdist
pcprint
mod255
xxhash
adler32
luhn
crc8smbus
crc15can
crc16
crc16hdlc
crc16usb
crc16citt
crc24
crc32
crc32c
crc32ecma267
crc32bzip2
crc32d
crc32mpeg2
crc32posix
crc32q
crc32jamcrc
crc32xfer
crc64
crc64ecma
crc64we
crc64xz
crc64iso

The ph command accepts an optional numeric argument to specify length of byte range to be hashed,
instead of default block size. For example:

286
Rahash2

[0x08049A80]> ph md5 32
9b9012b00ef7a94b5824105b7aaad83b
[0x08049A80]> ph md5 64
a71b087d8166c99869c9781e2edcf183
[0x08049A80]> ph md5 1024
a933cc94cd705f09a41ecc80c0041def

287
Rahash Tool

Examples
The rahash2 tool can be used to calculate checksums and has functions of byte streams, files, text
strings.

$ rahash2 -h
Usage: rahash2 [-rBhLkv] [-b S] [-a A] [-c H] [-E A] [-s S] [-f O] [-t O] [file] ...
-a algo comma separated list of algorithms (default is 'sha256')
-b bsize specify the size of the block (instead of full file)
-B show per-block hash
-c hash compare with this hash
-e swap endian (use little endian)
-E algo encrypt. Use -S to set key and -I to set IV
-D algo decrypt. Use -S to set key and -I to set IV
-f from start hashing at given address
-i num repeat hash N iterations
-I iv use give initialization vector (IV) (hexa or s:string)
-S seed use given seed (hexa or s:string) use ^ to prefix (key for -E)
(- will slurp the key from stdin, the @ prefix points to a file
-k show hash using the openssh's randomkey algorithm
-q run in quiet mode (-qq to show only the hash)
-L list all available algorithms (see -a)
-r output radare commands
-s string hash this string instead of files
-t to stop hashing at given address
-x hexstr hash this hexpair string instead of files
-v show version information

To obtain an MD5 hash value of a text string, use the -s option:

$ rahash2 -q -a md5 -s 'hello world'

5eb63bbbe01eeed093cb22bb8f5acdc3

It is possible to calculate hash values for contents of files. But do not attempt to do it for very large files
because rahash2 buffers the whole input in memory before computing the hash.

To apply all algorithms known to rahash2, use all as an algorithm name:

288
Rahash Tool

$ rahash2 -a all /bin/ls

/bin/ls: 0x00000000-0x000268c7 md5: 767f0fff116bc6584dbfc1af6fd48fc7
/bin/ls: 0x00000000-0x000268c7 sha1: 404303f3960f196f42f8c2c12970ab0d49e28971
/bin/ls: 0x00000000-0x000268c7 sha256: 74ea05150acf311484bddd19c608aa02e6bf3332a0f0805a4
deb278e17396354
/bin/ls: 0x00000000-0x000268c7 sha384: c6f811287514ceeeaabe73b5b2f54545036d6fd3a192ea5d6
a1fcd494d46151df4117e1c62de0884cbc174c8db008ed1
/bin/ls: 0x00000000-0x000268c7 sha512: 53e4950a150f06d7922a2ed732060e291bf0e1c2ac20bc72a
41b9303e1f2837d50643761030d8b918ed05d12993d9515e1ac46676bc0d15ac94d93d8e446fa09
/bin/ls: 0x00000000-0x000268c7 md4: fdfe7c7118a57c1ff8c88a51b16fc78c
/bin/ls: 0x00000000-0x000268c7 xor: 42
/bin/ls: 0x00000000-0x000268c7 xorpair: d391
/bin/ls: 0x00000000-0x000268c7 parity: 00
/bin/ls: 0x00000000-0x000268c7 entropy: 5.95471783
/bin/ls: 0x00000000-0x000268c7 hamdist: 00
/bin/ls: 0x00000000-0x000268c7 pcprint: 22
/bin/ls: 0x00000000-0x000268c7 mod255: ef
/bin/ls: 0x00000000-0x000268c7 xxhash: 76554666
/bin/ls: 0x00000000-0x000268c7 adler32: 7704fe60
/bin/ls: 0x00000000-0x000268c7 luhn: 01
/bin/ls: 0x00000000-0x000268c7 crc8smbus: 8d
/bin/ls: 0x00000000-0x000268c7 crc15can: 1cd5
/bin/ls: 0x00000000-0x000268c7 crc16: d940
/bin/ls: 0x00000000-0x000268c7 crc16hdlc: 7847
/bin/ls: 0x00000000-0x000268c7 crc16usb: 17bb
/bin/ls: 0x00000000-0x000268c7 crc16citt: 67f7
/bin/ls: 0x00000000-0x000268c7 crc24: 3e7053
/bin/ls: 0x00000000-0x000268c7 crc32: c713f78f
/bin/ls: 0x00000000-0x000268c7 crc32c: 6cfba67c
/bin/ls: 0x00000000-0x000268c7 crc32ecma267: b4c809d6
/bin/ls: 0x00000000-0x000268c7 crc32bzip2: a1884a09
/bin/ls: 0x00000000-0x000268c7 crc32d: d1a9533c
/bin/ls: 0x00000000-0x000268c7 crc32mpeg2: 5e77b5f6
/bin/ls: 0x00000000-0x000268c7 crc32posix: 6ba0dec3
/bin/ls: 0x00000000-0x000268c7 crc32q: 3166085c
/bin/ls: 0x00000000-0x000268c7 crc32jamcrc: 38ec0870
/bin/ls: 0x00000000-0x000268c7 crc32xfer: 7504089d
/bin/ls: 0x00000000-0x000268c7 crc64: b6471d3093d94241
/bin/ls: 0x00000000-0x000268c7 crc64ecma: b6471d3093d94241
/bin/ls: 0x00000000-0x000268c7 crc64we: 8fe37d44a47157bd
/bin/ls: 0x00000000-0x000268c7 crc64xz: ea83e12c719e0d79
/bin/ls: 0x00000000-0x000268c7 crc64iso: d243106d9853221c

289
Plugins

Plugins
radare2 is implemented on top of a bunch of libraries, almost every of those libraries support plugins to
extend the capabilities of the library or add support for different targets.

This section aims to explain what are the plugins, how to write them and use them

Types of plugins
$ ls libr/*/p | grep : | awk -F / '{ print $2 }'
anal # analysis plugins
asm # assembler/disassembler plugins
bin # binary format parsing plugins
bp # breakpoint plugins
core # core plugins (implement new commands)
crypto # encrypt/decrypt/hash/...
debug # debugger backends
egg # shellcode encoders, etc
fs # filesystems and partition tables
io # io plugins
lang # embedded scripting languages
parse # disassembler parsing plugins
reg # arch register logic

Listing plugins
Some r2 tools have the -L flag to list all the plugins associated to the functionality.

rasm2 -L # list asm plugins

r2 -L # list io plugins
rabin2 -L # list bin plugins
rahash2 -L # list hash/crypto/encoding plugins

There are more plugins in r2land, we can list them from inside r2, and this is done by using the L
suffix.

Those are some of the commands:

290
Plugins

L # list core plugins

iL # list bin plugins
dL # list debug plugins
mL # list fs plugins
ph # print support hash algoriths

But also using the ? value in the associated eval vars.

e asm.arch=? # list assembler/disassembler plugins

e anal.arch=? # list analysis plugins

Notes
Note there are some inconsistencies that most likely will be fixed in the future radare2 versions.

291
IO plugins

IO plugins
All access to files, network, debugger and all input/output in general is wrapped by an IO abstraction
layer that allows radare to treat all data as if it were just a file.

IO plugins are the ones used to wrap the open, read, write and 'system' on virtual file systems. You can
make radare understand anything as a plain file. E.g. a socket connection, a remote radare session, a file,
a process, a device, a gdb session.

So, when radare reads a block of bytes, it is the task of an IO plugin to get these bytes from any place
and put them into internal buffer. An IO plugin is chosen by a file's URI to be opened. Some examples:

Debugging URIs

$ r2 dbg:///bin/ls<br />
$ r2 pid://1927

Remote sessions

$ r2 rap://:1234<br />
$ r2 rap://<host>:1234//bin/ls

Virtual buffers

$ r2 malloc://512<br />
shortcut for
$ r2 -

You can get a list of the radare IO plugins by typing radare2 -L :

292
IO plugins

$ r2 -L
rw_ ar Open ar/lib files [ar|lib]://[file//path] (LGPL3)
rw_ bfdbg BrainFuck Debugger (bfdbg://path/to/file) (LGPL3)
rwd bochs Attach to a BOCHS debugger (LGPL3)
r_d debug Native debugger (dbg:///bin/ls dbg://1388 pidof:// waitfor://) (LGPL3)
v0.2.0 pancake
rw_ default open local files using def_mmap:// (LGPL3)
rwd gdb Attach to gdbserver, 'qemu -s', gdb://localhost:1234 (LGPL3)
rw_ gprobe open gprobe connection using gprobe:// (LGPL3)
rw_ gzip read/write gzipped files (LGPL3)
rw_ http http get (http://rada.re/) (LGPL3)
rw_ ihex Intel HEX file (ihex://eeproms.hex) (LGPL)
r__ mach mach debug io (unsupported in this platform) (LGPL)
rw_ malloc memory allocation (malloc://1024 hex://cd8090) (LGPL3)
rw_ mmap open file using mmap:// (LGPL3)
rw_ null null-plugin (null://23) (LGPL3)
rw_ procpid /proc/pid/mem io (LGPL3)
rwd ptrace ptrace and /proc/pid/mem (if available) io (LGPL3)
rwd qnx Attach to QNX pdebug instance, qnx://host:1234 (LGPL3)
rw_ r2k kernel access API io (r2k://) (LGPL3)
rw_ r2pipe r2pipe io plugin (MIT)
rw_ r2web r2web io client (r2web://cloud.rada.re/cmd/) (LGPL3)
rw_ rap radare network protocol (rap://:port rap://host:port/file) (LGPL3)
rw_ rbuf RBuffer IO plugin: rbuf:// (LGPL)
rw_ self read memory from myself using 'self://' (LGPL3)
rw_ shm shared memory resources (shm://key) (LGPL3)
rw_ sparse sparse buffer allocation (sparse://1024 sparse://) (LGPL3)
rw_ tcp load files via TCP (listen or connect) (LGPL3)
rwd windbg Attach to a KD debugger (windbg://socket) (LGPL3)
rwd winedbg Wine-dbg io and debug.io plugin for r2 (MIT)
rw_ zip Open zip files [apk|ipa|zip|zipall]://[file//path] (BSD)

293
Asm plugins

Implementing a new disassembly plugin

Radare2 has modular architecture, thus adding support for a new architecture is very easy, if you are
fluent in C. For various reasons it might be easier to implement it out of the tree. For this we will need
to create single C file, called asm_mycpu.c and makefile for it.

The key thing of RAsm plugin is a structure

RAsmPlugin r_asm_plugin_mycpu = {
.name = "mycpu",
.license = "LGPL3",
.desc = "MYCPU disassembly plugin",
.arch = "mycpu",
.bits = 32,
.endian = R_SYS_ENDIAN_LITTLE,
.disassemble = &disassemble
};

where .disassemble is a pointer to disassembly function, which accepts the bytes buffer and length:

static int disassemble(RAsm *a, RAsmOp *op, const ut8 *buf, int len)

Makefile

294
Asm plugins

NAME=asm_snes
R2_PLUGIN_PATH=$(shell r2 -H|grep USER_PLUGINS|awk '{print $$2}')
CFLAGS=-g -fPIC $(shell pkg-config --cflags r_anal)
LDFLAGS=-shared $(shell pkg-config --libs r_anal)
OBJS=$(NAME).o
SO_EXT=$(shell uname|grep -q Darwin && echo dylib || echo so)
LIB=$(NAME).$(SO_EXT)

all: $(LIB)

clean:
rm -f $(LIB) $(OBJS)

$(LIB): $(OBJS)
$(CC) $(CFLAGS) $(LDFLAGS) $(OBJS) -o $(LIB)

install:
cp -f asm_mycpu.$(SO_EXT) $(R2_PLUGIN_PATH)

uninstall:
rm -f $(R2_PLUGIN_PATH)/asm_mycpu.$(SO_EXT)

asm_mycpu.c

295
Asm plugins

#include <stdio.h>
#include <string.h>
#include <r_types.h>
#include <r_lib.h>
#include <r_asm.h>

static int disassemble(RAsm *a, RAsmOp *op, const ut8 *buf, int len) {
struct op_cmd cmd = {
.instr = "",
.operands = ""
};
if (len < 2) return -1;
int ret = decode_opcode (buf, len, &cmd);
if (ret > 0) {
snprintf (op->buf_asm, R_ASM_BUFSIZE, "%s %s",
cmd.instr, cmd.operands);
}
return op->size = ret;
}

RAsmPlugin r_asm_plugin_mycpu = {
.name = "mycpu",
.license = "LGPL3",
.desc = "MYCPU disassembly plugin",
.arch = "mycpu",
.bits = 32,
.endian = R_SYS_ENDIAN_LITTLE,
.disassemble = &disassemble
};

#ifndef CORELIB
RLibStruct radare_plugin = {
.type = R_LIB_TYPE_ASM,
.data = &r_asm_plugin_mycpu,
.version = R2_VERSION
};
#endif

After compiling radare2 will list this plugin in the output:

_d__ _8_32 mycpu LGPL3 MYCPU

Moving plugin into the tree

296
Asm plugins

Pushing a new architecture into the main branch of r2 requires to modify several files in order to make it
fit into the way the rest of plugins are built.

List of affected files:

plugins.def.cfg : add the asm.mycpu plugin name string in there

libr/asm/p/mycpu.mk : build instructions

libr/asm/p/asm_mycpu.c : implementation

libr/include/r_asm.h : add the struct definition in there

Check out how the NIOS II CPU disassembly plugin was implemented by reading those commits:

Implement RAsm plugin:

https://github.com/radare/radare2/commit/933dc0ef6ddfe44c88bbb261165bf8f8b531476b

Implement RAnal plugin:

https://github.com/radare/radare2/commit/ad430f0d52fbe933e0830c49ee607e9b0e4ac8f2

297
Analysis plugins

Implementing a new analysis plugin

After implementing disassembly plugin, you might have noticed that output is far from being good - no
proper highlighting, no reference lines and so on. This is because radare2 requires every architecture
plugin to provide also analysis information about every opcode. At the moment the implementation of
disassembly and opcodes analysis is separated between two modules - RAsm and RAnal. Thus we need
to write an analysis plugin too. The principle is very similar - you just need to create a C file and
corresponding Makefile.

They structure of RAnal plugin looks like

RAnalPlugin r_anal_plugin_v810 = {
.name = "mycpu",
.desc = "MYCPU code analysis plugin",
.license = "LGPL3",
.arch = "mycpu",
.bits = 32,
.op = mycpu_op,
.esil = true,
.set_reg_profile = set_reg_profile,
};

Like with disassembly plugin there is a key function - mycpu_op which scans the opcode and builds
RAnalOp structure. On the other hand, in this example analysis plugins also performs uplifting to ESIL,
which is enabled in .esil = true statement. Thus, mycpu_op obliged to fill the corresponding
RAnalOp ESIL field for the opcodes. Second important thing for ESIL uplifting and emulation - register
profile, like in debugger, which is set within set_reg_profile function.

Makefile

298
Analysis plugins

NAME=anal_snes
R2_PLUGIN_PATH=$(shell r2 -H|grep USER_PLUGINS|awk '{print $$2}')
CFLAGS=-g -fPIC $(shell pkg-config --cflags r_anal)
LDFLAGS=-shared $(shell pkg-config --libs r_anal)
OBJS=$(NAME).o
SO_EXT=$(shell uname|grep -q Darwin && echo dylib || echo so)
LIB=$(NAME).$(SO_EXT)

all: $(LIB)

clean:
rm -f $(LIB) $(OBJS)

$(LIB): $(OBJS)
$(CC) $(CFLAGS) $(LDFLAGS) $(OBJS) -o $(LIB)

install:
cp -f anal_snes.$(SO_EXT) $(R2_PLUGIN_PATH)

uninstall:
rm -f $(R2_PLUGIN_PATH)/anal_snes.$(SO_EXT)

anal_snes.c:

299
Analysis plugins

#include <string.h>
#include <r_types.h>
#include <r_lib.h>
#include <r_asm.h>
#include <r_anal.h>
#include "snes_op_table.h"

static int snes_anop(RAnal *anal, RAnalOp *op, ut64 addr, const ut8 *data, int len) {
memset (op, '\0', sizeof (RAnalOp));
op->size = snes_op[data[0]].len;
op->addr = addr;
op->type = R_ANAL_OP_TYPE_UNK;
switch (data[0]) {
case 0xea:
op->type = R_ANAL_OP_TYPE_NOP;
break;
}
return op->size;
}

struct r_anal_plugin_t r_anal_plugin_snes = {

.name = "snes",
.desc = "SNES analysis plugin",
.license = "LGPL3",
.arch = R_SYS_ARCH_NONE,
.bits = 16,
.init = NULL,
.fini = NULL,
.op = &snes_anop,
.set_reg_profile = NULL,
.fingerprint_bb = NULL,
.fingerprint_fcn = NULL,
.diff_bb = NULL,
.diff_fcn = NULL,
.diff_eval = NULL
};

#ifndef CORELIB
struct r_lib_struct_t radare_plugin = {
.type = R_LIB_TYPE_ANAL,
.data = &r_anal_plugin_snes,
.version = R2_VERSION
};
#endif

After compiling radare2 will list this plugin in the output:

300
Analysis plugins

_dA_ _8_16 snes LGPL3 SuperNES CPU

snes_op_table.h: https://github.com/radare/radare2/blob/master/libr/asm/arch/snes/snes_op_table.h

Example:

6502: https://github.com/radare/radare2/commit/64636e9505f9ca8b408958d3c01ac8e3ce254a9b
SNES: https://github.com/radare/radare2/commit/60d6e5a1b9d244c7085b22ae8985d00027624b49

301
Bin plugins

Implementing a new format

To enable virtual addressing
In info add et->has_va = 1; and ptr->srwx with the R_BIN_SCN_MAP; attribute

Create a folder with file format name in libr/bin/format

Makefile:

NAME=bin_nes
R2_PLUGIN_PATH=$(shell r2 -hh|grep R2_LIBR_PLUGINS|awk '{print $$2}')
CFLAGS=-g -fPIC $(shell pkg-config --cflags r_bin)
LDFLAGS=-shared $(shell pkg-config --libs r_bin)
OBJS=$(NAME).o
SO_EXT=$(shell uname|grep -q Darwin && echo dylib || echo so)
LIB=$(NAME).$(SO_EXT)

all: $(LIB)

clean:
rm -f $(LIB) $(OBJS)

$(LIB): $(OBJS)
$(CC) $(CFLAGS) $(LDFLAGS) $(OBJS) -o $(LIB)

install:
cp -f $(NAME).$(SO_EXT) $(R2_PLUGIN_PATH)

uninstall:
rm -f $(R2_PLUGIN_PATH)/$(NAME).$(SO_EXT)

bin_nes.c:

#include <r_bin.h>

static int check(RBinFile *arch);

static int check_bytes(const ut8 *buf, ut64 length);

static void * load_bytes(RBinFile *arch, const ut8 *buf, ut64 sz, ut64 loadaddr, Sdb *sd
b){
check_bytes (buf, sz);
return R_NOTNULL;
}
302
Bin plugins

static int check(RBinFile *arch) {

const ut8 \*bytes = arch ? r_buf_buffer (arch->buf) : NULL;
ut64 sz = arch ? r_buf_size (arch->buf): 0;
return check_bytes (bytes, sz);
}

static int check_bytes(const ut8 *buf, ut64 length) {

if (!buf || length < 4) return false;
return (!memcmp (buf, "\x4E\x45\x53\x1A", 4));
}

static RBinInfo* info(RBinFile *arch) {

RBinInfo \*ret = R_NEW0 (RBinInfo);
if (!ret) return NULL;

if (!arch || !arch->buf) {
free (ret);
return NULL;
}
ret->file = strdup (arch->file);
ret->type = strdup ("ROM");
ret->machine = strdup ("Nintendo NES");
ret->os = strdup ("nes");
ret->arch = strdup ("6502");
ret->bits = 8;

return ret;
}

struct r_bin_plugin_t r_bin_plugin_nes = {

.name = "nes",
.desc = "NES",
.license = "BSD",
.init = NULL,
.fini = NULL,
.get_sdb = NULL,
.load = NULL,
.load_bytes = &load_bytes,
.check = &check,
.baddr = NULL,
.check_bytes = &check_bytes,
.entries = NULL,
.sections = NULL,
.info = &info,
};

#ifndef CORELIB

303
Bin plugins

struct r_lib_struct_t radare_plugin = {

.type = R_LIB_TYPE_BIN,
.data = &r_bin_plugin_nes,
.version = R2_VERSION
};
#endif

Some Examples
XBE - https://github.com/radare/radare2/pull/972
COFF - https://github.com/radare/radare2/pull/645
TE - https://github.com/radare/radare2/pull/61
Zimgz - https://github.com/radare/radare2/commit/d1351cf836df3e2e63043a6dc728e880316f00eb
OMF - https://github.com/radare/radare2/commit/44fd8b2555a0446ea759901a94c06f20566bbc40

304
Other plugins

Write a debugger plugin

Adding the debugger registers profile into the shlr/gdb/src/core.c
Adding the registers profile and architecture support in the libr/debug/p/debug_native.c and
libr/debug/p/debug_gdb.c
Add the code to apply the profiles into the function r_debug_gdb_attach(RDebug *dbg, int pid)

If you want to add support for the gdb, you can see the register profile in the active gdb session using
command maint print registers .

More to come..
Related article: http://radare.today/posts/extending-r2-with-new-plugins/

Some commits related to "Implementing a new architecture"

Extensa: https://github.com/radare/radare2/commit/6f1655c49160fe9a287020537afe0fb8049085d7
Malbolge: https://github.com/radare/radare2/pull/579
6502: https://github.com/radare/radare2/pull/656
h8300: https://github.com/radare/radare2/pull/664
GBA: https://github.com/radare/radare2/pull/702
CR16: https://github.com/radare/radare2/pull/721/ && 726
XCore: https://github.com/radare/radare2/commit/bb16d1737ca5a471142f16ccfa7d444d2713a54d
SharpLH5801:
https://github.com/neuschaefer/radare2/commit/f4993cca634161ce6f82a64596fce45fe6b818e7
MSP430: https://github.com/radare/radare2/pull/1426
HP-PA-RISC:
https://github.com/radare/radare2/commit/f8384feb6ba019b91229adb8fd6e0314b0656f7b
V810: https://github.com/radare/radare2/pull/2899
TMS320: https://github.com/radare/radare2/pull/596

Implementing a new pseudo architecture

This is an simple plugin for z80 that you may use as example:

https://github.com/radare/radare2/commit/8ff6a92f65331cf8ad74cd0f44a60c258b137a06

305
Other plugins

306
Python plugins

Python plugins
At first, to be able to write a plugins in Python for radare2 you need to install r2lang plugin. If you're
going to use Python 2, then use r2pm -i lang-python2 , otherwise (and recommended) - install the
Python 3 version: r2pm -i lang-python3 . Note - in the following examples there are missing
functions of the actual decoding for the sake of readability!

For this you need to do this:

1. import r2lang and from r2lang import R (for constants)

2. Make a function with 2 subfunctions - assemble and disassemble and returning plugin
structure - for RAsm plugin

def mycpu(a):
def assemble(s):
return [1, 2, 3, 4]

def disassemble(buf):
try:
opcode = get_opcode(buf)
opstr = optbl[opcode][1]
return [4, opstr]
except:
return [4, "unknown"]

3. This structure should contain a pointers to these 2 functions - assemble and disassemble

return {
"name" : "mycpu",
"arch" : "mycpu",
"bits" : 32,
"endian" : "little",
"license" : "GPL",
"desc" : "MYCPU disasm",
"assemble" : assemble,
"disassemble" : disassemble,
}

1. Make a function with 2 subfunctions - set_reg_profile and op and returning plugin structure -
for RAnal plugin

307
Python plugins

def mycpu_anal(a):
def set_reg_profile():
profile = "=PC pc\n" + \
"=SP sp\n" + \
"gpr r0 .32 0 0\n" + \
"gpr r1 .32 4 0\n" + \
"gpr r2 .32 8 0\n" + \
"gpr r3 .32 12 0\n" + \
"gpr r4 .32 16 0\n" + \
"gpr r5 .32 20 0\n" + \
"gpr sp .32 24 0\n" + \
"gpr pc .32 28 0\n"
return profile

def op(addr, buf):

analop = {
"type" : R.R_ANAL_OP_TYPE_NULL,
"cycles" : 0,
"stackop" : 0,
"stackptr" : 0,
"ptr" : -1,
"jump" : -1,
"addr" : 0,
"eob" : False,
"esil" : "",
}
try:
opcode = get_opcode(buf)
esilstr = optbl[opcode][2]
if optbl[opcode][0] == "J": # it's jump
analop["type"] = R.R_ANAL_OP_TYPE_JMP
analop["jump"] = decode_jump(opcode, j_mask)
esilstr = jump_esil(esilstr, opcode, j_mask)

except:
result = analop
# Don't forget to return proper instruction size!
return [4, result]

1. This structure should contain a pointers to these 2 functions - set_reg_profile and op

308
Python plugins

return {
"name" : "mycpu",
"arch" : "mycpu",
"bits" : 32,
"license" : "GPL",
"desc" : "MYCPU anal",
"esil" : 1,
"set_reg_profile" : set_reg_profile,
"op" : op,
}

1. Then register those using r2lang.plugin("asm") and r2lang.plugin("anal") respectively

print("Registering MYCPU disasm plugin...")

print(r2lang.plugin("asm", mycpu))
print("Registering MYCPU analysis plugin...")
print(r2lang.plugin("anal", mycpu_anal))

You can combine everything in one file and load it using -i option:

r2 -I mycpu.py some_file.bin

Or you can load it from the r2 shell: #!python mycpu.py

Implementing new format plugin in Python

Note - in the following examples there are missing functions of the actual decoding for the sake of
readability!

For this you need to do this:

1. import r2lang

2. Make a function with subfunctions:

load

load_bytes

destroy

309
Python plugins

check_bytes

baddr

entries

sections

imports

relocs

binsym

info

and returning plugin structure - for RAsm plugin

def le_format(a):
def load(binf):
return [0]

def check_bytes(buf):
try:
if buf[0] == 77 and buf[1] == 90:
lx_off, = struct.unpack("<I", buf[0x3c:0x40])
if buf[lx_off] == 76 and buf[lx_off+1] == 88:
return [1]
return [0]
except:
return [0]

and so on. Please be sure of the parameters for each function and format of returns. Note, that
functions entries , sections , imports , relocs returns a list of special formed dictionaries -
each with a different type. Other functions return just a list of numerical values, even if single
element one. There is a special function, which returns information about the file - info :

def info(binf):
return [{
"type" : "le",
"bclass" : "le",
"rclass" : "le",
"os" : "OS/2",
"subsystem" : "CLI",
"machine" : "IBM",
"arch" : "x86",
"has_va" : 0,
"bits" : 32,
"big_endian" : 0,
"dbg_info" : 0,
}]

310
Python plugins

3. This structure should contain a pointers to the most important functions like check_bytes , load
and load_bytes , entries , relocs , imports .

return {
"name" : "le",
"desc" : "OS/2 LE/LX format",
"license" : "GPL",
"load" : load,
"load_bytes" : load_bytes,
"destroy" : destroy,
"check_bytes" : check_bytes,
"baddr" : baddr,
"entries" : entries,
"sections" : sections,
"imports" : imports,
"symbols" : symbols,
"relocs" : relocs,
"binsym" : binsym,
"info" : info,
}

1. Then you need to register it as a file format plugin:

print("Registering OS/2 LE/LX plugin...")

print(r2lang.plugin("bin", le_format))

311
Debugging

Debugging
It is common to have an issues when you write a plugin, especially if you do this for the first time. This
is why debugging them is very important. The first step for debugging is to set an environment variable
when running radare2 instance:

R_DEBUG=yes r2 /bin/ls
Loading /usr/local/lib/radare2/2.2.0-git//bin_xtr_dyldcache.so
Cannot find symbol 'radare_plugin' in library '/usr/local/lib/radare2/2.2.0-git//bin_xtr
_dyldcache.so'
Cannot open /usr/local/lib/radare2/2.2.0-git//2.2.0-git
Loading /home/user/.config/radare2/plugins/asm_mips_ks.so
PLUGIN OK 0x55b205ea6070 fcn 0x7f298de08762
Loading /home/user/.config/radare2/plugins/asm_sparc_ks.so
PLUGIN OK 0x55b205ea6070 fcn 0x7f298de08762
Cannot open /home/user/.config/radare2/plugins/pimp
Cannot open /home/user/.config/radare2/plugins/yara
Loading /home/user/.config/radare2/plugins/asm_arm_ks.so
PLUGIN OK 0x55b205ea6070 fcn 0x7f298de08762
Loading /home/user/.config/radare2/plugins/core_yara.so
Module version mismatch /home/user/.config/radare2/plugins/core_yara.so (2.1.0) vs (2.2.
0-git)
Loading /home/user/.config/radare2/plugins/asm_ppc_ks.so
PLUGIN OK 0x55b205ea6070 fcn 0x7f298de08762
Loading /home/user/.config/radare2/plugins/lang_python3.so
PLUGIN OK 0x55b205ea5ed0 fcn 0x7f298de08692
Loading /usr/local/lib/radare2/2.2.0-git/bin_xtr_dyldcache.so
Cannot find symbol 'radare_plugin' in library '/usr/local/lib/radare2/2.2.0-git/bin_xtr_
dyldcache.so'
Cannot open /usr/local/lib/radare2/2.2.0-git/2.2.0-git
Cannot open directory '/usr/local/lib/radare2-extras/2.2.0-git'
Cannot open directory '/usr/local/lib/radare2-bindings/2.2.0-git'
USER CONFIG loaded from /home/user/.config/radare2/radare2rc
-- In visual mode press 'c' to toggle the cursor mode. Use tab to navigate
[0x00005520]>

312
Testing

Testing the plugin

This plugin is used by rasm2 and r2. You can verify that the plugin is properly loaded with this
command:

$ rasm2 -L | grep mycpu

_d mycpu My CPU disassembler (LGPL3)

Let's open an empty file using the 'mycpu' arch and write some random code there.

$ r2 -
-- I endians swap
[0x00000000]> e asm.arch=mycpu
[0x00000000]> woR
[0x00000000]> pd 10
0x00000000 888e mov r8, 14
0x00000002 b2a5 ifnot r10, r5
0x00000004 3f67 ret
0x00000006 7ef6 bl r15, r6
0x00000008 2701 xor r0, 1
0x0000000a 9826 mov r2, 6
0x0000000c 478d xor r8, 13
0x0000000e 6b6b store r6, 11
0x00000010 1382 add r8, r2
0x00000012 7f15 ret

Yay! it works.. and the mandatory oneliner too!

r2 -nqamycpu -cwoR -cpd' 10' -

313
Packaging

Creating an r2pm package of the plugin

As you remember radare2 has its own packaging manager and we can easily add newly written plugin
for everyone to access.

All packages are located in radare2-pm repository, and have very simple text format.

R2PM_BEGIN

R2PM_GIT "https://github.com/user/mycpu"
R2PM_DESC "[r2-arch] MYCPU disassembler and analyzer plugins"

R2PM_INSTALL() {
${MAKE} clean
${MAKE} all || exit 1
${MAKE} install R2PM_PLUGDIR="${R2PM_PLUGDIR}"
}

R2PM_UNINSTALL() {
rm -f "${R2PM_PLUGDIR}/asm_mycpu."*
rm -f "${R2PM_PLUGDIR}/anal_mycpu."*
}

R2PM_END

Then add it in the /db directory of radare2-pm repository and send a pull request to the mainline.

314
Crackmes

Crackmes
Crackmes (from "crack me" challenge) are the training ground for reverse engineering people. This
section will go over tutorials on how to defeat various crackmes using r2.

315
IOLI

IOLI CrackMes
The IOLI crackme is a good starting point for learning r2. This is a set of tutorials based on the tutorial
at dustri

The IOLI crackmes are available at a locally hosted mirror

316
IOLI 0x00

IOLI 0x00
This is the first IOLI crackme, and the easiest one.

$ ./crackme0x00
IOLI Crackme Level 0x00
Password: 1234
Invalid Password!

The first thing to check is if the password is just plaintext inside the file. In this case, we don't need to
do any disassembly, and we can just use rabin2 with the -z flag to search for strings in the binary.

$ rabin2 -z ./crackme0x00
vaddr=0x08048568 paddr=0x00000568 ordinal=000 sz=25 len=24 section=.rodata type=a string
=IOLI Crackme Level 0x00\n
vaddr=0x08048581 paddr=0x00000581 ordinal=001 sz=11 len=10 section=.rodata type=a string
=Password:
vaddr=0x0804858f paddr=0x0000058f ordinal=002 sz=7 len=6 section=.rodata type=a string=2
50382
vaddr=0x08048596 paddr=0x00000596 ordinal=003 sz=19 len=18 section=.rodata type=a string
=Invalid Password!\n
vaddr=0x080485a9 paddr=0x000005a9 ordinal=004 sz=16 len=15 section=.rodata type=a string
=Password OK :)\n

So we know what the following section is, this section is the header shown when the application is run.

vaddr=0x08048568 paddr=0x00000568 ordinal=000 sz=25 len=24 section=.rodata type=a string

=IOLI Crackme Level 0x00\n

Here we have the prompt for the password.

vaddr=0x08048581 paddr=0x00000581 ordinal=001 sz=11 len=10 section=.rodata type=a string

=Password:

This is the error on entering an invalid password.

vaddr=0x08048596 paddr=0x00000596 ordinal=003 sz=19 len=18 section=.rodata type=a string

=Invalid Password!\n

317
IOLI 0x00

This is the message on the password being accepted.

vaddr=0x080485a9 paddr=0x000005a9 ordinal=004 sz=16 len=15 section=.rodata type=a string

=Password OK :)\n

But what is this? It's a string, but we haven't seen it in running the application yet.

vaddr=0x0804858f paddr=0x0000058f ordinal=002 sz=7 len=6 section=.rodata type=a string=2

50382

Let's give this a shot.

$ ./crackme0x00
IOLI Crackme Level 0x00
Password: 250382
Password OK :)

So we now know that 250382 is the password, and have completed this crackme.

318
IOLI 0x01

IOLI 0x01
This is the second IOLI crackme.

$ ./crackme0x01
IOLI Crackme Level 0x01
Password: test
Invalid Password!

Let's check for strings with rabin2.

$ rabin2 -z ./crackme0x01
vaddr=0x08048528 paddr=0x00000528 ordinal=000 sz=25 len=24 section=.rodata type=a string
=IOLI Crackme Level 0x01\n
vaddr=0x08048541 paddr=0x00000541 ordinal=001 sz=11 len=10 section=.rodata type=a string
=Password:
vaddr=0x0804854f paddr=0x0000054f ordinal=002 sz=19 len=18 section=.rodata type=a string
=Invalid Password!\n
vaddr=0x08048562 paddr=0x00000562 ordinal=003 sz=16 len=15 section=.rodata type=a string
=Password OK :)\n

This isn't going to be as easy as 0x00. Let's try disassembly with r2.

319
IOLI 0x01

$ r2 ./crackme0x01
-- Use `zoom.byte=printable` in zoom mode ('z' in Visual mode) to find strings
[0x08048330]> aa
[0x08048330]> pdf@main
/ (fcn) main 113
| ; var int local_4 @ ebp-0x4
| ; DATA XREF from 0x08048347 (entry0)
| 0x080483e4 55 push ebp
| 0x080483e5 89e5 mov ebp, esp
| 0x080483e7 83ec18 sub esp, 0x18
| 0x080483ea 83e4f0 and esp, -0x10
| 0x080483ed b800000000 mov eax, 0
| 0x080483f2 83c00f add eax, 0xf
| 0x080483f5 83c00f add eax, 0xf
| 0x080483f8 c1e804 shr eax, 4
| 0x080483fb c1e004 shl eax, 4
| 0x080483fe 29c4 sub esp, eax
| 0x08048400 c7042428850. mov dword [esp], str.IOLI_Crackme_Level_0x01_n ; [
0x8048528:4]=0x494c4f49 ; "IOLI Crackme Level 0x01." @ 0x8048528
| 0x08048407 e810ffffff call sym.imp.printf
| sym.imp.printf(unk)
| 0x0804840c c7042441850. mov dword [esp], str.Password_ ; [0x8048541:4]=0x7
3736150 ; "Password: " @ 0x8048541
| 0x08048413 e804ffffff call sym.imp.printf
| sym.imp.printf()
| 0x08048418 8d45fc lea eax, dword [ebp + 0xfffffffc]
| 0x0804841b 89442404 mov dword [esp + 4], eax ; [0x4:4]=0x10101
| 0x0804841f c704244c850. mov dword [esp], 0x804854c ; [0x804854c:4]=0x49006
425 ; "%d" @ 0x804854c
| 0x08048426 e8e1feffff call sym.imp.scanf
| sym.imp.scanf()
| 0x0804842b 817dfc9a140. cmp dword [ebp + 0xfffffffc], 0x149a
| ,=< 0x08048432 740e je 0x8048442
| | 0x08048434 c704244f850. mov dword [esp], str.Invalid_Password__n ; [0x8048
54f:4]=0x61766e49 ; "Invalid Password!." @ 0x804854f
| | 0x0804843b e8dcfeffff call sym.imp.printf
| | sym.imp.printf()
| ,==< 0x08048440 eb0c jmp 0x804844e ; (main)
| || ; JMP XREF from 0x08048432 (main)
| |`-> 0x08048442 c7042462850. mov dword [esp], str.Password_OK____n ; [0x8048562
:4]=0x73736150 ; "Password OK :)." @ 0x8048562
| | 0x08048449 e8cefeffff call sym.imp.printf
| | sym.imp.printf()
| | ; JMP XREF from 0x08048440 (main)
| `--> 0x0804844e b800000000 mov eax, 0
| 0x08048453 c9 leave
\ 0x08048454 c3 ret

"aa" tells r2 to analyze the whole binary, which gets you symbol names, among things.
320
IOLI 0x01

"pdf" stands for

Disassemble

Function

This will print the disassembly of the main function, or the main() that everyone knows. You can see
several things as well: weird names, arrows, etc.

"imp." stands for imports. Those are imported symbols, like printf()

"str." stands for strings. Those are strings (obviously).

If you look carefully, you'll see a cmp instruction, with a constant, 0x149a. cmp is an x86 compare
instruction, and the 0x in front of it specifies it is in base 16, or hex (hexadecimal).

0x0804842b 817dfc9a140. cmp dword [ebp + 0xfffffffc], 0x149a

You can use radare2's ? command to get it in another numeric base.

[0x08048330]> ? 0x149a
5274 0x149a 012232 5.2K 0000:049a 5274 10011010 5274.0 0.000000

So now we know that 0x149a is 5274 in decimal. Let's try this as a password.

$ ./crackme0x01
IOLI Crackme Level 0x01
Password: 5274
Password OK :)

Bingo, the password was 5274. In this case, the password function at 0x0804842b was comparing the
input against the value, 0x149a in hex. Since user input is usually decimal, it was a safe bet that the
input was intended to be in decimal, or 5274. Now, since we're hackers, and curiosity drives us, let's see
what happens when we input in hex.

$ ./crackme0x01
IOLI Crackme Level 0x01
Password: 0x149a
Invalid Password!

321
IOLI 0x01

It was worth a shot, but it doesn't work. That's because scanf() will take the 0 in 0x149a to be a zero,
rather than accepting the input as actually being the hex value.

And this concludes IOLI 0x01.

322
IOLI 0x01

.intro
After a few years of missing out on wargames at Hacktivity, this year I've finally found the time to
begin, and almost finish (yeah, I'm quite embarrassed about that unfinished webhack :) ) one of them.
There were 3 different games at the conf, and I've chosen the one that was provided by avatao. It
consisted of 8 challenges, most of them being basic web hacking stuff, one sandbox escape, one simple
buffer overflow exploitation, and there were two reverse engineering exercises too. You can find these
challenges on https://platform.avatao.com.

323
IOLI 0x01

.radare2
I've decided to solve the reversing challenges using radare2, a free and open source reverse engineering
framework. I have first learned about r2 back in 2011. during a huge project, where I had to reverse a
massive, 11MB statically linked ELF. I simply needed something that I could easily patch Linux ELFs
with. Granted, back then I've used r2 alongside IDA, and only for smaller tasks, but I loved the whole
concept at first sight. Since then, radare2 evolved a lot, and I was planning for some time now to solve
some crackmes with the framework, and write writeups about them. Well, this CTF gave me the perfect
opportunity :)

Because this writeup aims to show some of r2's features besides how the crackmes can be solved, I will
explain every r2 command I use in blockquote paragraphs like this one:

r2 tip: Always use ? or -h to get more information!

If you know r2, and just interested in the crackme, feel free to skip those parts! Also keep in mind
please, that because of this tutorial style I'm going to do a lot of stuff that you just don't do during a
CTF, because there is no time for proper bookkeeping (e.g. flag every memory area according to its
purpose), and with such small executables you can succeed without doing these stuff.

A few advice if you are interested in learning radare2 (and frankly, if you are into RE, you should be
interested in learning r2 :) ):

The framework has a lot of supplementary executables and a vast amount of functionality - and they are
very well documented. I encourage you to read the available docs, and use the built-in help (by
appending a ? to any command) extensively! E.g.:

324
IOLI 0x01

...

...

Also, the project is under heavy development, there is no day without commits to the GitHub repo. So,
as the readme says, you should always use the git version!

Some highly recommended reading materials:

Cheatsheet by pwntester
Radare2 Book
Radare2 Blog
Radare2 Wiki

325
IOLI 0x01

.first_steps
OK, enough of praising r2, lets start reversing this stuff. First, you have to know your enemy:

[0x00 avatao]$ rabin2 -I reverse4

pic false
canary true
nx true
crypto false
va true
intrp /lib64/ld-linux-x86-64.so.2
bintype elf
class ELF64
lang c
arch x86
bits 64
machine AMD x86-64 architecture
os linux
subsys linux
endian little
stripped true
static false
linenum false
lsyms false
relocs false
rpath NONE
binsz 8620

r2 tip: rabin2 is one of the handy tools that comes with radare2. It can be used to extract
information (imports, symbols, libraries, etc.) about binary executables. As always, check the
help (rabin2 -h)!

So, its a dynamically linked, stripped, 64bit Linux executable - nothing fancy here. Let's try to run it:

[0x00 avatao]$ ./reverse4

?
Size of data: 2623
pamparam
Wrong!

[0x00 avatao]$ "\x01\x00\x00\x00" | ./reverse4

Size of data: 1

326
IOLI 0x01

OK, so it reads a number as a size from the standard input first, than reads further, probably "size"
bytes/characters, processes this input, and outputs either "Wrong!", nothing or something else,
presumably our flag. But do not waste any more time monkeyfuzzing the executable, let's fire up r2,
because in asm we trust!

[0x00 avatao]$ r2 -A reverse4

-- Heisenbug: A bug that disappears or alters its behavior when one attempts to probe o
r isolate it.
[0x00400720]>

r2 tip: The -A switch runs aaa command at start to analyze all referenced code, so we will have
functions, strings, XREFS, etc. right at the beginning. As usual, you can get help with ?.

It is a good practice to create a project, so we can save our progress, and we can come back at a later
time:

[0x00400720]> Ps avatao_reverse4
avatao_reverse4
[0x00400720]>

r2 tip: You can save a project using Ps [file], and load one using Po [file]. With the -p option,
you can load a project when starting r2.

We can list all the strings r2 found:

[0x00400720]> fs strings
[0x00400720]> f
0x00400e98 7 str.Wrong_
0x00400e9f 27 str.We_are_in_the_outer_space_
0x00400f80 18 str.Size_of_data:__u_n
0x00400f92 23 str.Such_VM__MuCH_reV3rse_
0x00400fa9 16 str.Use_everything_
0x00400fbb 9 str.flag.txt
0x00400fc7 26 str.You_won__The_flag_is:__s_n
0x00400fe1 21 str.Your_getting_closer_
[0x00400720]>

r2 tip: r2 puts so called flags on important/interesting offsets, and organizes these flags into
flagspaces (strings, functions, symbols, etc.) You can list all flagspaces using fs, and switch the
current one using fs [flagspace] (the default is *, which means all the flagspaces). The command
f prints all flags from the currently selected flagspace(s).

327
IOLI 0x01

OK, the strings looks interesting, especially the one at 0x00400f92. It seems to hint that this crackme is
based on a virtual machine. Keep that in mind!

These strings could be a good starting point if we were talking about a real-life application with many-
many features. But we are talking about a crackme, and they tend to be small and simple, and focused
around the problem to be solved. So I usually just take a look at the entry point(s) and see if I can figure
out something from there. Nevertheless, I'll show you how to find where these strings are used:

[0x00400720]> axt @@=`f~[0]`

d 0x400cb5 mov edi, str.Size_of_data:__u_n
d 0x400d1d mov esi, str.Such_VM__MuCH_reV3rse_
d 0x400d4d mov edi, str.Use_everything_
d 0x400d85 mov edi, str.flag.txt
d 0x400db4 mov edi, str.You_won__The_flag_is:__s_n
d 0x400dd2 mov edi, str.Your_getting_closer_

r2 tip: We can list crossreferences to addresses using the axt [addr] command (similarly, we can
use axf to list references from the address). The @@ is an iterator, it just runs the command once
for every arguments listed.

The argument list in this case comes from the command f~[0]. It lists the strings from the
executable with f, and uses the internal grep command ~ to select only the first column ([0]) that
contains the strings' addresses.

328
IOLI 0x01

.main
As I was saying, I usually take a look at the entry point, so let's just do that:

[0x00400720]> s main
[0x00400c63]>

r2 tip: You can go to any offset, flag, expression, etc. in the executable using the s command
(seek). You can use references, like $$ (current offset), you can undo (s-) or redo (s+) seeks,
search strings (s/ [string]) or hex values (s/x 4142), and a lot of other useful stuff. Make sure to
check out s?!

Now that we are at the beginning of the main function, we could use p to show a disassembly (pd, pdf),
but r2 can do something much cooler: it has a visual mode, and it can display graphs similar to IDA, but
way cooler, since they are ASCII-art graphs :)

r2 tip: The command family p is used to print stuff. For example it can show disassembly (pd),
disassembly of the current function (pdf), print strings (ps), hexdump (px), base64 encode/decode
data (p6e, p6d), or print raw bytes (pr) so you can for example dump parts of the binary to other
files. There are many more functionalities, check ?!

R2 also has a minimap view which is incredibly useful for getting an overall look at a function:

329
IOLI 0x01

330
IOLI 0x01

r2 tip: With command V you can enter the so-called visual mode, which has several views. You
can switch between them using p and P. The graph view can be displayed by hitting V in visual
mode (or using VV at the prompt).

Hitting p in graph view will bring up the minimap. It displays the basic blocks and the
connections between them in the current function, and it also shows the disassembly of the
currently selected block (marked with @@@@@ on the minimap). You can select the next or
the previous block using the *\* and the *\\* keys respectively. You can also select the true or the
false branches using the t and the f keys.

It is possible to bring up the prompt in visual mode using the : key, and you can use o to seek.

Lets read main node-by-node! The first block looks like this:

We can see that the program reads a word (2 bytes) into the local variable named local_10_6, and than
compares it to 0xbb8. Thats 3000 in decimal, btw:

[0x00400c63]> ? 0xbb8
3000 0xbb8 05670 2.9K 0000:0bb8 3000 10111000 3000.0 0.000000f 0.000000

r2 tip: yep, ? will evaluate expressions, and print the result in various formats.

331
IOLI 0x01

If the value is greater than 3000, then it will be forced to be 3000:

There are a few things happening in the next block:

First, the "Size of data: " message we saw when we run the program is printed. So now we know that
the local variable local_10_6 is the size of the input data - so lets name it accordingly (remember, you
can open the r2 shell from visual mode using the : key!):

:> afvn local_10_6 input_size

332
IOLI 0x01

r2 tip: The af command family is used to analyze functions. This includes manipulating
arguments and local variables too, which is accessible via the afv commands. You can list
function arguments (afa), local variables (afv), or you can even rename them (afan, afvn). Of
course there are lots of other features too - as usual: use the "?", Luke!

After this an input_size bytes long memory chunk is allocated, and filled with data from the standard
input. The address of this memory chunk is stored in local_10 - time to use afvn again:

:> afvn local_10 input_data

We've almost finished with this block, there are only two things remained. First, an 512 (0x200) bytes
memory chunk is zeroed out at offset 0x00602120. A quick glance at XREFS to this address reveals that
this memory is indeed used somewhere in the application:

:> axt 0x00602120

d 0x400cfe mov edi, 0x602120
d 0x400d22 mov edi, 0x602120
d 0x400dde mov edi, 0x602120
d 0x400a51 mov qword [rbp - 8], 0x602120

Since it probably will be important later on, we should label it:

:> f sym.memory 0x200 0x602120

r2 tip: Flags can be managed using the f command family. We've just added the flag
sym.memory to a 0x200 bytes long memory area at 0x602120. It is also possible to remove (f-
name), rename (fr [old] [new]), add comment (fC [name] [cmt]) or even color (fc [name]
[color]) flags.

While we are here, we should also declare that memory chunk as data, so it will show up as a hexdump
in disassembly view:

:> Cd 0x200 @ sym.memory

r2 tip: The command family C is used to manage metadata. You can set (CC) or edit (CC)
comments, declare memory areas as data (Cd), strings (Cs), etc. These commands can also be
issued via a menu in visual mode invoked by pressing d.

333
IOLI 0x01

The only remaining thing in this block is a function call to 0x400a45 with the input data as an argument.
The function's return value is compared to "*", and a conditional jump is executed depending on the
result.

Earlier I told you that this crackme is probably based on a virtual machine. Well, with that information
in mind, one can guess that this function will be the VM's main loop, and the input data is the
instructions the VM will execute. Based on this hunch, I've named this function vmloop, and renamed
input_data to bytecode and input_size to bytecode_length. This is not really necessary in a small project
like this, but it's a good practice to name stuff according to their purpose (just like when you are writing
programs).

:> af vmloop 0x400a45

:> afvn input_size bytecode_length
:> afvn input_data bytecode

r2 tip: The af command is used to analyze a function with a given name at the given address. The
other two commands should be familiar from earlier.

After renaming local variables, flagging that memory area, and renaming the VM loop function the
disassembly looks like this:

334
IOLI 0x01

So, back to that conditional jump. If vmloop returns anything else than "*", the program just exits
without giving us our flag. Obviously we don't want that, so we follow the false branch.

Now we see that a string in that 512 bytes memory area (sym.memory) gets compared to "Such VM!
MuCH reV3rse!". If they are not equal, the program prints the bytecode, and exits:

OK, so now we know that we have to supply a bytecode that will generate that string when executed. As
we can see on the minimap, there are still a few more branches ahead, which probably means more
conditions to meet. Lets investigate them before we delve into vmloop!

If you take a look at the minimap of the whole function, you can probably recognize that there is some
kind of loop starting at block [0d34], and it involves the following nodes:

[0d34]
[0d65]
[0d3d]
[0d61]

Here are the assembly listings for those blocks. The first one puts 0 into local variable local_10_4:

335
IOLI 0x01

And this one compares local_10_4 to 8, and executing a conditional jump based on the result:

It's pretty obvious that local_10_4 is the loop counter, so lets name it accordingly:

:> afvn local_10_4 i

Next block is the actual loop body:

336
IOLI 0x01

The memory area at 0x6020e0 is treated as an array of dwords (4 byte values), and checked if the ith
value of it is zero. If it is not, the loop simply continues:

If the value is zero, the loop breaks and this block is executed before exiting:

337
IOLI 0x01

It prints the following message: Use everything!" As we've established earlier, we are dealing with a
virtual machine. In that context, this message probably means that we have to use every available
instructions. Whether we executed an instruction or not is stored at 0x6020e0 - so lets flag that memory
area:

:> f sym.instr_dirty 4*9 0x6020e0

Assuming we don't break out and the loop completes, we are moving on to some more checks:

This piece of code may look a bit strange if you are not familiar with x86_64 specific stuff. In
particular, we are talking about RIP-relative addressing, where offsets are described as displacements
from the current instruction pointer, which makes implementing PIE easier. Anyways, r2 is nice enough
to display the actual address (0x602104). Got the address, flag it!

:> f sym.good_if_ne_zero 4 0x602104

Keep in mind though, that if RIP-relative addressing is used, flags won't appear directly in the
disassembly, but r2 displays them as comments:
338
IOLI 0x01

If sym.good_if_ne_zero is zero, we get a message ("Your getting closer!"), and then the program exits. If
it is non-zero, we move to the last check:

Here the program compares a dword at 0x6020f0 (again, RIP-relative addressing) to 9. If its greater
than 9, we get the same "Your getting closer!" message, but if it's lesser, or equal to 9, we finally reach
our destination, and get the flag:

339
IOLI 0x01

As usual, we should flag 0x6020f0:

:> f sym.good_if_le_9 4 0x6020f0

Well, it seems that we have fully reversed the main function. To summarize it: the program reads a
bytecode from the standard input, and feeds it to a virtual machine. After VM execution, the program's
state have to satisfy these conditions in order to reach the goodboy code:

vmloop's return value has to be "*"

sym.memory has to contain the string "Such VM! MuCH reV3rse!"
all 9 elements of sym.instr_dirty array should not be zero (probably means that all instructions had
to be used at least once)
sym.good_if_ne_zero should not be zero
sym.good_if_le_9 has to be lesser or equal to 9

This concludes our analysis of the main function, we can now move on to the VM itself.

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.vmloop
[offset]> fcn.vmloop

Well, that seems disappointingly short, but no worries, we have plenty to reverse yet. The thing is that
this function uses a jump table at 0x00400a74,

and r2 can't yet recognize jump tables (Issue 3201), so the analysis of this function is a bit incomplete.
This means that we can't really use the graph view now, so either we just use visual mode, or fix those
basic blocks. The entire function is just 542 bytes long, so we certainly could reverse it without the aid
of the graph mode, but since this writeup aims to include as much r2 wisdom as possible, I'm going to
show you how to define basic blocks.

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But first, lets analyze what we already have! First, rdi is put into local_3. Since the application is a 64bit
Linux executable, we know that rdi is the first function argument (as you may have recognized, the
automatic analysis of arguments and local variables was not entirely correct), and we also know that
vmloop's first argument is the bytecode. So lets rename local_3:

:> afvn local_3 bytecode

Next, sym.memory is put into another local variable at rbp-8 that r2 did not recognize. So let's define it!

:> afv 8 memory qword

r2 tip: The afv [idx] [name] [type] command is used to define local variable at [frame pointer -
idx] with the name [name] and type [type]. You can also remove local variables using the afv-
[idx] command.

In the next block, the program checks one byte of bytecode, and if it is 0, the function returns with 1.

If that byte is not zero, the program subtracts 0x41 from it, and compares the result to 0x17. If it is
above 0x17, we get the dreaded "Wrong!" message, and the function returns with 0. This basically
means that valid bytecodes are ASCII characters in the range of "A" (0x41) through "X" (0x41 + 0x17).
If the bytecode is valid, we arrive at the code piece that uses the jump table:

The jump table's base is at 0x400ec0, so lets define that memory area as a series of qwords:

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[0x00400a74]> s 0x00400ec0
[0x00400ec0]> Cd 8 @@=`?s $$ $$+8*0x17 8`

r2 tip: Except for the ?s, all parts of this command should be familiar now, but lets recap it! Cd
defines a memory area as data, and 8 is the size of that memory area. @@ is an iterator that
make the preceding command run for every element that @@ holds. In this example it holds a
series generated using the ?s command. ?s simply generates a series from the current seek ($$) to
current seek + 80x17 ($$+80x17) with a step of 8.

This is how the disassembly looks like after we add this metadata:

[0x00400ec0]> pd 0x18
; DATA XREF from 0x00400a76 (unk)
0x00400ec0 .qword 0x0000000000400a80
0x00400ec8 .qword 0x0000000000400c04
0x00400ed0 .qword 0x0000000000400b6d
0x00400ed8 .qword 0x0000000000400b17
0x00400ee0 .qword 0x0000000000400c04
0x00400ee8 .qword 0x0000000000400c04
0x00400ef0 .qword 0x0000000000400c04
0x00400ef8 .qword 0x0000000000400c04
0x00400f00 .qword 0x0000000000400aec
0x00400f08 .qword 0x0000000000400bc1
0x00400f10 .qword 0x0000000000400c04
0x00400f18 .qword 0x0000000000400c04
0x00400f20 .qword 0x0000000000400c04
0x00400f28 .qword 0x0000000000400c04
0x00400f30 .qword 0x0000000000400c04
0x00400f38 .qword 0x0000000000400b42
0x00400f40 .qword 0x0000000000400c04
0x00400f48 .qword 0x0000000000400be5
0x00400f50 .qword 0x0000000000400ab6
0x00400f58 .qword 0x0000000000400c04
0x00400f60 .qword 0x0000000000400c04
0x00400f68 .qword 0x0000000000400c04
0x00400f70 .qword 0x0000000000400c04
0x00400f78 .qword 0x0000000000400b99

As we can see, the address 0x400c04 is used a lot, and besides that there are 9 different addresses. Lets
see that 0x400c04 first!

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We get the message "Wrong!", and the function just returns 0. This means that those are not valid
instructions (they are valid bytecode though, they can be e.g. parameters!) We should flag 0x400c04
accordingly:

[0x00400ec0]> f not_instr @ 0x0000000000400c04

As for the other offsets, they all seem to be doing something meaningful, so we can assume they belong
to valid instructions. I'm going to flag them using the instructions' ASCII values:

[0x00400ec0]> f instr_A @ 0x0000000000400a80

[0x00400ec0]> f instr_C @ 0x0000000000400b6d
[0x00400ec0]> f instr_D @ 0x0000000000400b17
[0x00400ec0]> f instr_I @ 0x0000000000400aec
[0x00400ec0]> f instr_J @ 0x0000000000400bc1
[0x00400ec0]> f instr_P @ 0x0000000000400b42
[0x00400ec0]> f instr_R @ 0x0000000000400be5
[0x00400ec0]> f instr_S @ 0x0000000000400ab6
[0x00400ec0]> f instr_X @ 0x0000000000400b99

Ok, so these offsets were not on the graph, so it is time to define basic blocks for them!

r2 tip: You can define basic blocks using the afb+ command. You have to supply what function
the block belongs to, where does it start, and what is its size. If the block ends in a jump, you
have to specify where does it jump too. If the jump is a conditional jump, the false branch's
destination address should be specified too.

We can get the start and end addresses of these basic blocks from the full disasm of vmloop.

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As I've mentioned previously, the function itself is pretty short, and easy to read, especially with our
annotations. But a promise is a promise, so here is how we can create the missing bacic blocks for the
instructions:

[0x00400ec0]> afb+ 0x00400a45 0x00400a80 0x00400ab6-0x00400a80 0x400c15

[0x00400ec0]> afb+ 0x00400a45 0x00400ab6 0x00400aec-0x00400ab6 0x400c15
[0x00400ec0]> afb+ 0x00400a45 0x00400aec 0x00400b17-0x00400aec 0x400c15
[0x00400ec0]> afb+ 0x00400a45 0x00400b17 0x00400b42-0x00400b17 0x400c15
[0x00400ec0]> afb+ 0x00400a45 0x00400b42 0x00400b6d-0x00400b42 0x400c15
[0x00400ec0]> afb+ 0x00400a45 0x00400b6d 0x00400b99-0x00400b6d 0x400c15
[0x00400ec0]> afb+ 0x00400a45 0x00400b99 0x00400bc1-0x00400b99 0x400c15
[0x00400ec0]> afb+ 0x00400a45 0x00400bc1 0x00400be5-0x00400bc1 0x400c15
[0x00400ec0]> afb+ 0x00400a45 0x00400be5 0x00400c04-0x00400be5 0x400c15

It is also apparent from the disassembly that besides the instructions there are three more basic blocks.
Lets create them too!

[0x00400ec0]> afb+ 0x00400a45 0x00400c15 0x00400c2d-0x00400c15 0x400c3c 0x00400c2d

[0x00400ec0]> afb+ 0x00400a45 0x00400c2d 0x00400c3c-0x00400c2d 0x400c4d 0x00400c3c
[0x00400ec0]> afb+ 0x00400a45 0x00400c3c 0x00400c4d-0x00400c3c 0x400c61

Note that the basic blocks starting at 0x00400c15 and 0x00400c2d ending in a conditional jump, so we
had to set the false branch's destination too!

And here is the graph in its full glory after a bit of manual restructuring:

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I think it worth it, don't you? :) (Well, the restructuring did not really worth it, because it is apparently
not stored when you save the project.)

r2 tip: You can move the selected node around in graph view using the HJKL keys.

BTW, here is how IDA's graph of this same function looks like for comparison:

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As we browse through the disassembly of the instr_LETTER basic blocks, we should realize a few
things. The first: all of the instructions starts with a sequence like these:

It became clear now that the 9 dwords at sym.instr_dirty are not simply indicators that an instruction got
executed, but they are used to count how many times an instruction got called. Also I should have
realized earlier that sym.good_if_le_9 (0x6020f0) is part of this 9 dword array, but yeah, well, I didn't, I
have to live with it... Anyways, what the condition "sym.good_if_le_9 have to be lesser or equal 9"
really means is that instr_P can not be executed more than 9 times:

Another similarity of the instructions is that 7 of them calls a function with either one or two
parameters, where the parameters are the next, or the next two bytecodes. One parameter example:

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And a two parameters example:

We should also realize that these blocks put the number of bytes they eat up of the bytecode (1 byte
instruction + 1 or 2 bytes arguments = 2 or 3) into a local variable at 0xc. r2 did not recognize this local
var, so lets do it manually!

:> afv 0xc instr_ptr_step dword

If we look at instr_J we can see that this is an exception to the above rule, since it puts the return value
of the called function into instr_ptr_step instead of a constant 2 or 3:

And speaking of exceptions, here are the two instructions that do not call functions:

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This one simply puts the next bytecode (the first the argument) into eax, and jumps to the end of
vmloop. So this is the VM's ret instruction, and we know that vmloop has to return "*", so "R*" should
be the last two bytes of our bytecode.

The next one that does not call a function:

This is a one argument instruction, and it puts its argument to 0x6020c0. Flag that address!

:> f sym.written_by_instr_C 4 @ 0x6020c0

Oh, and by the way, I do have a hunch that instr_C also had a function call in the original code, but it
got inlined by the compiler. Anyways, so far we have these two instructions:

instr_R(a1): returns with a1

instr_C(a1): writes a1 to sym.written_by_instr_C

And we also know that these accept one argument,

instr_I
instr_D
instr_P
instr_X
instr_J

and these accept two:

instr_A
instr_S

What remains is the reversing of the seven functions that are called by the instructions, and finally the
construction of a valid bytecode that gives us the flag.

instr_A

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The function this instruction calls is at offset 0x40080d, so lets seek there!

[offset]> 0x40080d

r2 tip: In visual mode you can just hit \ when the current line is a jump or a call, and r2 will seek
to the destination address.

If we seek to that address from the graph mode, we are presented with a message that says "Not in a
function. Type 'df' to define it here. This is because the function is called from a basic block r2 did not
recognize, so r2 could not find the function either. Lets obey, and type df! A function is indeed created,
but we want some meaningful name for it. So press dr while still in visual mode, and name this function
instr_A!

r2 tip: You should realize that these commands are all part of the same menu system in visual
mode I was talking about when we first used Cd to declare sym.memory as data.

Ok, now we have our shiny new fcn.instr_A, lets reverse it! We can see from the shape of the minimap
that probably there is some kind cascading if-then-elif, or a switch-case statement involved in this
function. This is one of the reasons the minimap is so useful: you can recognize some patterns at a

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glance, which can help you in your analysis (remember the easily recognizable for loop from a few
paragraphs before?) So, the minimap is cool and useful, but I've just realized that I did not yet show you
the full graph mode, so I'm going to do this using full graph. The first basic blocks:

The two function arguments (rdi and rsi) are stored in local variables, and the first is compared to 0. If it
is, the function returns (you can see it on the minimap), otherwise the same check is executed on the
second argument. The function returns from here too, if the argument is zero. Although this function is
really tiny, I am going to stick with my methodology, and rename the local vars:

:> afvn local_1 arg1

:> afvn local_2 arg2

And we have arrived to the predicted switch-case statement, and we can see that arg1's value is checked
against "M", "P", and "C".

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This is the "M" branch:

It basically loads an address from offset 0x602088 and adds arg2 to the byte at that address. As r2
kindly shows us in a comment, 0x602088 initially holds the address of sym.memory, the area where we
have to construct the "Such VM! MuCH reV3rse!" string. It is safe to assume that somehow we will be
able to modify the value stored at 0x602088, so this "M" branch will be able to modify bytes other than
the first. Based on this assumption, I'll flag 0x602088 as sym.current_memory_ptr:

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:> f sym.current_memory_ptr 8 @ 0x602088

Moving on to the "P" branch:

Yes, this is the piece of code that allows us to modify sym.current_memory_ptr: it adds arg2 to it.

Finally, the "C" branch:

Well, it turned out that instr_C is not the only instruction that modifies sym.written_by_instr_C: this
piece of code adds arg2 to it.

And that was instr_A, lets summarize it! Depending on the first argument, this instruction does the
following:

arg1 == "M": adds arg2 to the byte at sym.current_memory_ptr.

arg1 == "P": steps sym.current_memory_ptr by arg2 bytes.
arg1 == "C": adds arg2 to the value at sym.written_by_instr_C.

instr_S
This function is not recognized either, so we have to manually define it like we did with instr_A. After
we do, and take a look at the minimap, scroll through the basic blocks, it is pretty obvious that these two
functions are very-very similar. We can use radiff2 to see the difference.

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r2 tip: radiff2 is used to compare binary files. There's a few options we can control the type of
binary diffing the tool does, and to what kind of output format we want. One of the cool features
is that it can generate DarumGrim-style bindiff graphs using the -g option.

Since now we want to diff two functions from the same binary, we specify the offsets with -g, and use
reverse4 for both binaries. Also, we create the graphs for comparing instr_A to instr_S and for
comparing instr_S to instr_A.

[0x00 ~]$ radiff2 -g 0x40080d,0x40089f reverse4 reverse4 | xdot -

[0x00 ~]$ radiff2 -g 0x40089f,0x40080d reverse4 reverse4 | xdot -

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A sad truth reveals itself after a quick glance at these graphs: radiff2 is a liar! In theory, grey boxes
should be identical, yellow ones should differ only at some offsets, and red ones should differ seriously.
Well this is obviously not the case here - e.g. the larger grey boxes are clearly not identical. This is
something I'm definitely going to take a deeper look at after I've finished this writeup.

Anyways, after we get over the shock of being lied to, we can easily recognize that instr_S is basically a
reverse-instr_A: where the latter does addition, the former does subtraction. To summarize this:

arg1 == "M": subtracts arg2 from the byte at sym.current_memory_ptr.

arg1 == "P": steps sym.current_memory_ptr backwards by arg2 bytes.
arg1 == "C": subtracts arg2 from the value at sym.written_by_instr_C.

instr_I

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This one is simple, it just calls instr_A(arg1, 1). As you may have noticed the function call looks like
call fcn.0040080d instead of call fcn.instr_A . This is because when you save and open a project,

function names get lost - another thing to examine and patch in r2!

instr_D

Again, simple: it calls instr_S(arg1, 1).

instr_P
It's local var rename time again!

:> afvn local_0_1 const_M

:> afvn local_0_2 const_P
:> afvn local_3 arg1

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This function is pretty straightforward also, but there is one oddity: const_M is never used. I don't know
why it is there - maybe it is supposed to be some kind of distraction? Anyways, this function simply
writes arg1 to sym.current_memory_ptr, and than calls instr_I("P"). This basically means that instr_P is
used to write one byte, and put the pointer to the next byte. So far this would seem the ideal instruction
to construct most of the "Such VM! MuCH reV3rse!" string, but remember, this is also the one that can
be used only 9 times!

instr_X
Another simple one, rename local vars anyways!

:> afvn local_1 arg1

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This function XORs the value at sym.current_memory_ptr with arg1.

instr_J
This one is not as simple as the previous ones, but it's not that complicated either. Since I'm obviously
obsessed with variable renaming:

:> afvn local_3 arg1

:> afvn local_0_4 arg1_and_0x3f

After the result of arg1 & 0x3f is put into a local variable, arg1 & 0x40 is checked against 0. If it isn't
zero, arg1_and_0x3f is negated:

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The next branching: if arg1 >= 0, then the function returns arg1_and_0x3f,

else the function branches again, based on the value of sym.written_by_instr_C:

If it is zero, the function returns 2,

else it is checked if arg1_and_0x3f is a negative number,

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and if it is, sym.good_if_ne_zero is incremented by 1:

After all this, the function returns with arg1_and_0x3f:

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.instructionset
We've now reversed all the VM instructions, and have a full understanding about how it works. Here is
the VM's instruction set:

Instruction 1st arg 2nd arg What does it do?

"A" "M" arg2 *sym.current_memory_ptr += arg2

"P" arg2 sym.current_memory_ptr += arg2

"C" arg2 sym.written_by_instr_C += arg2

"S" "M" arg2 *sym.current_memory_ptr -= arg2

"P" arg2 sym.current_memory_ptr -= arg2

"C" arg2 sym.written_by_instr_C -= arg2

"I" arg1 n/a instr_A(arg1, 1)

"D" arg1 n/a instr_S(arg1, 1)

"P" arg1 n/a *sym.current_memory_ptr = arg1; instr_I("P")

"X" arg1 n/a *sym.current_memory_ptr ^= arg1

arg1_and_0x3f = arg1 & 0x3f;

if (arg1 & 0x40 != 0)
arg1_and_0x3f *= -1
if (arg1 >= 0) return arg1_and_0x3f;
"J" arg1 n/a else if (*sym.written_by_instr_C != 0) {
if (arg1_and_0x3f < 0)
++*sym.good_if_ne_zero;
return arg1_and_0x3f;
} else return 2;

"C" arg1 n/a *sym.written_by_instr_C = arg1

"R" arg1 n/a return(arg1)

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.bytecode
Well, we did the reverse engineering part, now we have to write a program for the VM with the
instruction set described in the previous paragraph. Here is the program's functional specification:

the program must return "*"

sym.memory has to contain the string "Such VM! MuCH reV3rse!" after execution
all 9 instructions have to be used at least once
sym.good_if_ne_zero should not be zero
instr_P is not allowed to be used more than 9 times

Since this document is about reversing, I'll leave the programming part to the fellow reader :) But I'm
not going to leave you empty-handed, I'll give you one advice: Except for "J", all of the instructions are
simple, easy to use, and it should not be a problem to construct the "Such VM! MuCH reV3rse!" using
them. "J" however is a bit complicated compared to the others. One should realize that its sole purpose
is to make sym.good_if_ne_zero bigger than zero, which is a requirement to access the flag. In order to
increment sym.good_if_ne_zero, three conditions should be met:

arg1 should be a negative number, otherwise we would return early

sym.written_by_instr_C should not be 0 when "J" is called. This means that "C", "AC", or "SC"
instructions should be used before calling "J".
arg1_and_0x3f should be negative when checked. Since 0x3f's sign bit is zero, no matter what
arg1 is, the result of arg1 & 0x3f will always be non-negative. But remember that "J" negates
arg1_and_0x3f if arg1 & 0x40 is not zero. This basically means that arg1's 6th bit should be 1
(0x40 = 01000000b). Also, because arg1_and_0x3f can't be 0 either, at least one of arg1's 0th, 1st,
2nd, 3rd, 4th or 5th bits should be 1 (0x3f = 00111111b).

I think this is enough information, you can go now and write that program. Or, you could just reverse
engineer the quick'n'dirty one I've used during the CTF:

\x90\x00PSAMuAP\x01AMcAP\x01AMhAP\x01AM AP\x01AMVAP\x01AMMAP\x01AM!AP\x01AM AP\x01AMMAP\

x01AMuAP\x01AMCAP\x01AMHAP\x01AM AP\x01AMrAP\x01AMeAP\x01AMVAP\x01AM3AP\x01AMrAP\x01AMsA
P\x01AMeIPAM!X\x00CAJ\xc1SC\x00DCR*

Keep in mind though, that it was written on-the-fly, parallel to the reversing phase - for example there
are parts that was written without the knowledge of all possible instructions. This means that the code is
ugly and unefficient.

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.outro
Well, what can I say? Such VM, much reverse! :)

What started out as a simple writeup for a simple crackme, became a rather lengthy writeup/r2 tutorial,
so kudos if you've read through it. I hope you enjoyed it (I know I did), and maybe even learnt
something from it. I've surely learnt a lot about r2 during the process, and I've even contributed some
small patches, and got a few ideas of more possible improvements.

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Radare2 Reference Card

This chapter is based on the Radare 2 reference card by Thanat0s, which is under the GNU GPL.
Original license is as follows:

This card may be freely distributed under the terms of the GNU
general public licence — Copyright by Thanat0s - v0.1 -

Survival Guide
Those are the basic commands you will want to know and use for moving around a binary and getting
information about it.

Command Description

s (tab) Seek to a different place

x [nbytes] Hexdump of nbytes, $b by default

aa Auto analyze

pdf@fcn(Tab) Disassemble function

f fcn(Tab) List functions

f str(Tab) List strings

fr [flagname] [newname] Rename flag

psz [offset]~grep Print strings and grep for one

arf [flag] Find cross reference for a flag

Flags
Flags are like bookmarks, but they carry some extra information like size, tags or associated flagspace.
Use the f command to list, set, get them.

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Command Description

f List flags

fd $$ Describe an offset

fj Display flags in JSON

fl Show flag length

fx Show hexdump of flag

fC [name] [comment] Set flag comment

Flagspaces
Flags are created into a flagspace, by default none is selected, and listing flags will list them all. To
display a subset of flags you can use the fs command to restrict it.

Command Description

fs Display flagspaces

fs * Select all flagspaces

fs [sections] Select one flagspace

Information
Binary files have information stored inside the headers. The i command uses the RBin api and allows
us to the same things rabin2 do. Those are the most common ones.

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Command Description

ii Information on imports

iI Info on binary

ie Display entrypoint

iS Display sections

ir Display relocations

iz List strings (izz, izzz)

Print string
There are different ways to represent a string in memory. The ps command allows us to print it in utf-
16, pascal, zero terminated, .. formats.

Command Description

psz [offset] Print zero terminated string

psb [offset] Print strings in current block

psx [offset] Show string with scaped chars

psp [offset] Print pascal string

psw [offset] Print wide string

Visual mode
The visual mode is the standard interactive interface of radare2.

To enter in visual mode use the v or V command, and then you'll only have to press keys to get the
actions happen instead of commands.

Command Description

V Enter visual mode

p/P Rotate modes (hex, disasm, debug, words, buf)

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c Toggle (c)ursor

q Back to Radare shell

hjkl Move around (or HJKL) (left-down-up-right)

Enter Follow address of jump/call

sS Step/step over

o Go/seek to given offset

. Seek to program counter

/ In cursor mode, search in current block

:cmd Run radare command

;[-]cmt Add/remove comment

x+-/[] Change block size, [] = resize hex.cols

>||< Seek aligned to block size

i/a/A (i)nsert hex, (a)ssemble code, visual (A)ssembler

b/B Toggle breakpoint / automatic block size

d[f?] Define function, data, code, ..

D Enter visual diff mode (set diff.from/to)

e Edit eval configuration variables

f/F Set/unset flag

gG Go seek to begin and end of file (0-$s)

mK/’K Mark/go to Key (any key)

M Walk the mounted filesystems

n/N Seek next/prev function/flag/hit (scr.nkey)

o Go/seek to given offset

C Toggle (C)olors

R Randomize color palette (ecr)

t Track flags (browse symbols, functions..)

T Browse anal info and comments

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v Visual code analysis menu

V/W (V)iew graph (agv?), open (W)ebUI

uU Undo/redo seek

x Show xrefs to seek between them

yY Copy and paste selection

z Toggle zoom mode

Searching
There are many situations where we need to find a value inside a binary or in some specific regions.
Use the e search.in=? command to choose where the / command may search for the given value.

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Command Description

/ foo\00 Search for string ’foo\0’

/b Search backwards

// Repeat last search

/w foo Search for wide string ’f\0o\0o\0’

/wi foo Search for wide string ignoring case

/! ff Search for first occurrence not matching

/i foo Search for string ’foo’ ignoring case

/e /E.F/i Match regular expression

/x ff0.23 Search for hex string

/x ff..33 Search for hex string ignoring some nibbles

/x ff43 ffd0 Search for hexpair with mask

/d 101112 Search for a deltified sequence of bytes

/!x 00 Inverse hexa search (find first byte != 0x00)

/c jmp [esp] Search for asm code (see search.asmstr)

/a jmp eax Assemble opcode and search its bytes

/A Search for AES expanded keys

/r sym.printf Analyze opcode reference an offset

/R Search for ROP gadgets

/P Show offset of previous instruction

/m magicfile Search for matching magic file

/p patternsize Search for pattern of given size

/z min max Search for strings of given size

/v[?248] num Look for a asm.bigendian 32bit value

Saving
371
Reference Card

By default, when you open a file in write mode ( r2 -w ) all changes will be written directly into the
file. No undo history is saved by default.

Use e io.cache.write=true and the wc command to manage the write cache history changes. To
undo, redo, commit them to write the changes on the file..

But, if we want to save the analysis information, comments, flags and other user-created metadata, we
may want to use projects with r2 -p and the P command.

Command Description

Po [file] Open project

Ps [file] Save project

Pi [file] Show project information

Usable variables in expression

The ?$? command will display the variables that can be used in any math operation inside the r2 shell.
For example, using the ? $$ command to evaluate a number or ?v to just the the value in one
format.

All commands in r2 that accept a number supports the use of those variables.

Command Description

$$ here (current virtual seek)

$$$ current non-temporary virtual seek

$? last comparison value

$alias=value alias commands (simple macros)

$b block size

$B base address (aligned lowest map address)

$f jump fail address (e.g. jz 0x10 => next instruction)

$fl flag length (size) at current address (fla; pD $l @ entry0)

$F current function size

$FB begin of function

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Reference Card

$Fb address of the current basic block

$Fs size of the current basic block

$FE end of function

$FS function size

$Fj function jump destination

$Ff function false destination

$FI function instructions

$c,$r get width and height of terminal

$Cn get nth call of function

$Dn get nth data reference in function

$D current debug map base address ?v $D @ rsp

$DD current debug map size

$e 1 if end of block, else 0

$j jump address (e.g. jmp 0x10, jz 0x10 => 0x10)

$Ja get nth jump of function

$Xn get nth xref of function

$l opcode length

$m opcode memory reference (e.g. mov eax,[0x10] => 0x10)

$M map address (lowest map address)

$o here (current disk io offset)

$p getpid()

$P pid of children (only in debug)

$s file size

$S section offset

$SS section size

$v opcode immediate value (e.g. lui a0,0x8010 => 0x8010)

373
Reference Card

$w get word size, 4 if asm.bits=32, 8 if 64, ...

${ev} get value of eval config variable

$r{reg} get value of named register

$k{kv} get value of an sdb query value

$s{flag} get size of flag

RNum $variables usable in math expressions

374
Acknowledgments

Authors & Contributors

This book wouldn't be possible without the help of a large list of contributors who have been reviewing,
writing and reporting bugs and stuff in the radare2 project as well as in this book.

The radare2 book

This book was started by maijin as a new version of the original radare book written by pancake.

Old radare1 book http://www.radare.org/get/radare.pdf

Many thanks to everyone who has been involved with the gitbook:

Adrian Studer, Ahmed Mohamed Abd El-MAwgood, Akshay Krishnan R, Andrew Hoog, Anton
Kochkov, Antonio Sánchez, Austin Hartzheim, Bob131, DZ_ruyk, David Tomaschik, Eric, Fangrui
Song, Francesco Tamagni, FreeArtMan, Gerardo García Peña, Giuseppe, Grigory Rechistov, Hui Peng,
ITAYC0HEN, Itay Cohen, Jeffrey Crowell, John, Judge Dredd (key 6E23685A), Jupiter, Kevin
Grandemange, Kevin Laeufer, Luca Di Bartolomeo, Lukas Dresel, Maijin, Michael Scherer, Mike,
Nikita Abdullin, Paul, Paweł Łukasik, Peter C, RandomLive, Ren Kimura, Reto Schneider,
SchumBlubBlub, SkUaTeR, Solomon, Srimanta Barua, Sushant Dinesh, TDKPS, Thanat0s, Vanellope,
Vex Woo, Vorlent, XYlearn, Yuri Slobodyanyuk, ali, aoighost, condret, hdznrrd, izhuer, jvoisin, kij,
madblobfish, muzlightbeer, pancake, polym (Tim), puddl3glum, radare, sghctoma, shakreiner,
sivaramaaa, taiyu, vane11ope, xarkes.

375

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