Module XIV SQL Injection Ethical Hacking Module XIV SQL Injection

Module Objective What is SQL Injection? Exploiting the weakness of Server Side Scripting Using SQL Injection techniques to gain access to a system SQL Injection Scripts Attacking Microsoft SQL Servers MSSQL Password Crackers Prevention and Countermeasures

Introduction - SQL Injection

OLE DB Errors The user filled fields are enclosed by single quotation marks ('). So a simple test of the form would be to try using (') as the username. Lets us see what happens if we just enter ' in a form that is vulnerable to SQL insertion. If you get this error, then we can try SQL injection techniques.

Input Validation attack Input validation attack occurs here on a website

Login Guessing & Insertion The attacker can try to login without a password. Typical usernames would be 1=1 or any text within single quotes. The most common problem seen on Microsoft MS-SQL boxes is the default <blank>sa password. The attacker can try to guess the username of an account by querying for similar user names (ex: ‘ad%’ is used to query for “admin”). The attacker can insert data by appending commands or writing queries.

Shutting Down SQL Server One of SQL Server's most powerful commands is SHUTDOWN WITH NOWAIT, which causes it to shutdown, immediately stopping the Windows service. Username: ' ; shutdown with nowait; -- Password [Anything] This can happen if the script runs the following query: select userName from users where userName='; shutdown with nowait;-' and user_Pass=' '

Extended Stored Procedures There are several extended stored procedures that can cause permanent damage to a system. We can execute an extended stored procedure using our login form with an injected command as the username as follows: Username: ' ; exec master..xp_xxx; -- Password: [Anything] Username: ' ; exec master..xp_cmdshell ' iisreset' ; --

SQL Server Talks! This command uses the 'speech.voicetext' object, causing the SQL Server to speak:

Hacking Tool: SQLDict http://ntsecurity.nu/cgi-bin/download/sqldict.exe.pl "SQLdict" is a dictionary attack tool for SQL Server. It lets you test if the accounts are strong enough to resist an attack or not.

Hacking Tool: SQLExec This tool executes commands on compromised MIcrosoft SQL Servers using xp_cmdshell stored procedure. It uses default sa account with NULL password. But this can be modified easily. USAGE: SQLExec www.target.com

Hacking Tool: sqlbf http://www.cqure.net/tools.jsp?id=10 Sqlbf is a SQL Sever Password Auditing tool. This tool should be used to audit the strength of Microsoft SQL Server passwords offline. The tool can be used either in BruteForce mode or in Dictionary attack mode. The performance on a 1GHZ pentium (256MB) machine is around 750,000 guesses/sec. To be able to perform an audit, one needs the password hashes that are stored in the sysxlogins table in the master database. The hashes are easy to retrieve although you need a privileged account to do so, like an sa account. The query to use would be: select name, password from master..sysxlogins To perform a dictionary attack on the retrieved hashes: sqlbf -u hashes.txt -d dictionary.dic -r out.rep

Hacking Tool: SQLSmack SQLSmack is a Linux based Remote Command Execution for MSSQL. The tool allows when provided with a valid username and password on a remote MS SQL Server to execute commands by piping them through the stored procedure master..xp_cmdshell

Hacking Tool: SQL2.exe SQL2 is a UDP Buffer Overflow Remote Exploit hacking tool.

Preventive Measures Minimize Privileges of Database Connection Disable verbose error messages Protect the system account ‘sa’ Audit Source Code Escape Single Quotes Allow only good input Reject known bad input Restrict length of input

Summary SQL Injection is an attack methodology that targets the data residing in a database through the firewall that shields it. It attempts to modify the parameters of a Web-based application in order to alter the SQL statements that are parsed to retrieve data from the database. Database footprinting is the process of mapping out the tables on the database and is a crucial tool in the hands of an attacker. Exploits occur due to coding errors as well as inadequate validation checks . Prevention involves enforcing better coding practices and database administration procedures.