Signature Detail

HTTP: SQL Character Encoding Evasion in URL

This signature detects SQL commands with character conversion within a URL. The char() function converts hexadecimal and decimal values into characters to be interpreted by the SQL engine. By encoding common injection variables, attackers can attempt to evade detection. Because SQL commands are not normally used in HTTP connections, this can indicate a SQL injection attack. However, it can be a false positive. To reduce false positives, it is strongly recommended that these signatures only be used to inspect traffic from the Internet to your organization's Web servers that use SQL backend databases to generate content and not to inspect traffic going from your organization to the Internet.

Extended Description

By manipulating SQL queries in the URL, a malicious user is able to guide the execution flow of a SQL server to cause unexpected operations in the SQL backend. This results in data leaks, or false authentications.

References

• URL: http://www.securityfocus.com/infocus/1768
• URL: http://ferruh.mavituna.com/sql-injection-cheatsheet-oku/#UsingIntegers