[TheLastSuperman]

That's actually a very old modification, was for use before the additional.css template was added (4.x in the beginning did not have additional.css template) but if you're unsure who installed it then follow Amaury's advice and uninstall. If your running 4.2.x then simply uninstall it, the additional.css template parses just fine in newer versions of vBulletin .

You're also free to post the plugin code here for us to review and reply back as to whether its malicious or not, if your site was hacked, depending on how the hacker may have edited plugins and added malicious code to any plugin etc etc.

Edit: Also if I'm not mistaken that was packaged with some styles by certain authors, would be older skins but just thought to mention.