Is your Apache server getting pummeled by all those requests ment to exploit IIS? Well check out MSIISProbes.pm
In response to the growing number of worms attemtping to exploit vulnerabilities in Microsoft software, Tonkin Resolutions is making available MSIISProbes.pm, a Perl module for the Apache web server that detects such attacks and responds by sending e-mail to Security Focus and to the administrators of the culprit server.
If you run Apache and Perl through mod_perl and would like to try the module, it is available here.