I tried searching for this mod for vBulletin but cant find one.
Got this idea from the WHMCS client software forum here
http://forum.whmcs.com/showthread.php?p=55959#post55959 this link is to the original whmcs thread and has the attached files for you coders to get some ideas so you can convert to vBulletin. Note: I can also send the files to coders if you need them for evaluation. Just pm me.
Basically its a fake adminCP that looks real and allows would be hackers to try and login but they end up getting a fake database error. It also records the username, IP address, and password they used and emails it to the email address you specify. Hopefully they just think your forum is screwed up and they quit trying.
This would be great for all of us that have changed the location of the original admin and mod CP folders.
Thanks