Something has changed with a vbulletin update recently, because there has been a surge of spam within the last month or two. I don’t own any forums on the bulletin, but I’m guessing there is a little bit of configuration that got overwritten when an update happened. I reported roughly a dozen spam threads this morning, and they were popping up as I was reporting others. With how difficult vbulletin is to do things from CLI, I doubt that a script is doing this unless somebody invested a lot of time in the a script that would make registration and post a thread. That could completely be the case, but vbulletin makes it difficult to web scrape with auth.Having been an admin on multiple forums from everything from SimpleMachine software, Vbulletin, etc... there are steps that can be deployed for the user registration process that greatly limits the amount of trash that gets in.
edit: that was more general information, not directed at you.