I just was made aware of a suspicious file in my last server backup by Microsoft Security Essentials. This file was hidden in the forum’s cache on the live site as well.
As such I am going to take the forums down for a while and install a clean copy.
I’ll try to keep everyone up to day here on this post and on Twitter @infiniunreal.
Update 1: I originally contacted Invision Power about it, they said it probably was a hack attempt and to use their steps for cleaning up. I took the scorched-earth method and just deleted the entire forum directory, made an entirely new database setup, and changed EVERYONE’s FTP passwords.
Nothing should have been lost since I backed up the original files and the original database is still intact.
Update 2: I think everything is back up on the forums. I might have missed some images here and there, but I’ll upload those if I find them.