Really private forums?
 

The default behavior in vBulletin is that a "private" forum will automatically be viewable by any new usergroup you add to the system.

This is a big problem in sites that need a large number of private forums with separate groups.

Has anyone written a modification for vBulletin that addresses this problem? I found one for 2.x, but I was hoping for an updated version that works in 3.6. Basically, I'd like to be able to flag new private forums as "private" that causes all existing and future groups to be denied access unless they are explicitly granted access via the usergroup manager.

(Incidentally, deny-by-default is the standard in just about every access control scheme ever invented--why isn't this already a feature in vBulletin? If it is, and I'm missing something, please inform me. I'd love to be wrong on this.)