Chapter 15 Unified Threat Management for FortiOS 5.0 : Security Profiles overview : Traffic inspection : IPS signatures
  
IPS signatures
IPS signatures can detect malicious network traffic. For example, the Code Red worm attacked a vulnerability in the Microsoft IIS web server. Your FortiGate’s IPS system can detect traffic attempting to exploit this vulnerability. IPS may also detect when infected systems communicate with servers to receive instructions.