What I need is a forensic log analyzer tool for apache to do the after math of a successful abuse of service attack which took place 2-3 month in the past. We are running a shared hosting service and one of our customers seems to have (or had) an exploitable script running. I suspect that I could find clues and hints in the logs but they are just too huge to browse through them manually or grep regexps from them.
Is there a tool which can do it and has predefined search patterns for known attacks and probably even heuristics to discover suspicious activities?
I do not look for a tool to do real-time blocking of such attempts because I need to analyze past logs and see if the exploit has been closed.