IBM Web Application Firewall, as used on the G400 IPS-G400-IB-1 and GX4004 IPS-GX4004-IB-2 appliances with update 31.030, does not properly handle query strings with multiple instances of the same parameter, which allows remote attackers to bypass intended intrusion prevention by dividing a dangerous parameter value into substrings, as demonstrated by a SQL statement that is split across multiple iid parameters and then sent to a .aspx file on an IIS web server.