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0% found this document useful (0 votes)
32 views10 pagesSQL Injection
Uploaded by
Gustavo RochaCopyright
© © All Rights Reserved
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
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SQL injection
Server-side data
Client Server
Browser Web server
Long-lived state, stored
(Private)
in a separate database
Data
Database
Need to protect this
state from illicit access
and tampering
Server-side data
• Typically want ACID transactions
• Atomicity!
- Transactions complete entirely or not at all
• Consistency!
- The database is always in a valid state
• Isolation!
- Results from a transaction aren’t visible until it is complete
• Durability
- Once a transaction is committed, its effects persist despite, e.g.,
power failures
• Database Management Systems (DBMSes)
provide these properties (and then some)
SQL (Standard Query Language)
Table
Users Table name
Name Gender Age Email Password
Dee F 28 dee@pp.com j3i8g8ha
Mac M 7 bouncer@pp.com a0u23bt
Row!
Charlie M 32 readgood@pp.com
aneifjask@pp.com 0aergja
(Record)
Dennis M 28 imagod@pp.com 1bjb9a93
Frank M 57 armed@pp.com ziog9gga
Column
SELECT Age FROM Users WHERE Name=‘Dee’; 28
UPDATE Users SET email=‘readgood@pp.com’
WHERE Age=32; -- this is a comment
INSERT INTO Users Values(‘Frank’, ‘M’, 57, ...);
DROP TABLE Users;
Server-side code
Website
“Login code” (PHP)
$result = mysql_query(“select * from Users!
where(name=‘$user’ and password=‘$pass’);”);
Suppose you successfully log in as $user
if this returns any results
How could you exploit this?
SQL injection
frank’ OR 1=1); --
$result = mysql_query(“select * from Users!
where(name=‘$user’ and password=‘$pass’);”);
$result = mysql_query(“select * from Users!
where(name=‘frank’ OR 1=1); --!
! ! ! and password=‘whocares’);”);
SQL injection
frank’ OR 1=1); DROP TABLE Users; --
$result = mysql_query(“select * from Users!
where(name=‘$user’ and password=‘$pass’);”);
$result = mysql_query(“select * from Users!
where(name=‘frank’ OR 1=1);!
DROP TABLE Users; --!
! ! ! and password=‘whocares’);”);
Can chain together statements with semicolon:
STATEMENT 1 ; STATEMENT 2
SQL injection attacks are common
20
15 % of vulnerabilities that
are SQL injection
10
0
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03
04
05
06
07
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09
10
11
12
13
14
20
20
20
20
20
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20
20
20
http://web.nvd.nist.gov/view/vuln/statistics
http://xkcd.com/327/