We’ve read a lot recently about attacks in which an attacker loads a modified module into Apache to insert iframes in outgoing data. Pretty scary, especially since nobody really seems to know how the hacks are performed. Recently, Sucuri wrote a blog article about how to check for rogue Apache modules on Debian. We’ve decided to implement this into an Icinga/Nagios check.
Hope this helps!
Update: I packaged and pushed the wrong version of the script… Silly me. Fixed now!