UBB.threads PHP Forum Software Community Forums Resources and Customizing How Do I? Block URLs / UBB in Signatures?

Spammers are becoming more industrious - now they post a meaningless post and their signature has spammy 'make millions at home' links. I want to ban all URLs from signatures except for my moderators. I can find how to block images from signatures (which I've done) but not how to block UBB code from signatures ...

Lisa