Please read this important announcement about a security issue with your version of vB:
http://www.vbulletin.com/forum/showt...180#post694180
It is not related to the PHP worm, but this does need to be patched. I strongly recommend upgrading to at least 2.3.5 ASAP.
Please read this announcement concerning the phpBB worm and your vBulletin forums:
http://www.vbulletin.com/forum/showthread.php?t=124008