An intrusion detection system for customizing a security policy that detects an attempt to exploit a vulnerability is provided. A security policy contains criteria and a procedure. The criteria specify attributes of a security event that may be an exploitation, and the procedure specifies instructions to be performed that indicate when a security event may be an exploitation. When the criteria and the procedure both indicate that a security event may be an exploitation, then the security event matches the security policy and an appropriate action is taken. The intrusion detection system allows a user to modify the criteria to customize the security policy.