SQL injection

SQL injection is a code injection technique, used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker).SQL injection must exploit a security vulnerability in an application's software, for example, when user input is either incorrectly filtered for string literal escape characters embedded in SQL statements or user input is not strongly typed and unexpectedly executed. SQL injection is mostly known as an attack vector for websites but can be used to attack any type of SQL database.


SQL injection (SQLI) is considered one of the top 10 web application vulnerabilities of 2007 and 2010 by the Open Web Application Security Project. In 2013, SQLI was rated the number one attack on the OWASP top ten. There are four main sub-classes of SQL injection:

• Classic SQLI
• Blind or Inference SQL injection
• Database management system-specific SQLI
• Compounded SQLI

• SQL injection + insufficient authentication
• SQL injection +DDos attacks
• SQL injection + DNS hijacking
• SQL injection + XSS

The Storm Worm is one representation of Compounded SQLI.
This classification represents the state of SQLI, respecting its evolution until 2010—further refinement is underway.