A white paper from the Imperva Application Defense Center entitled ‘SQL Injection Signature Evasion’. This paper discusses how protecting against SQL injection attacks using signatures is not enough.
You can download it from the following link: https://packetstormsecurity.com/files/download/33120/SQL_Injection_Evasion.pdf
Source: https://packetstormsecurity.com/files/33120/SQL_Injection_Evasion.pdf.html