Well if you want to dig since you have admin access:
GOTO
Control Panel » View Admin Logs
And search through for evidence of permission changes.
The log will show anyone who made changes to the site.
It can be very large if you have not purged it in a while.
Depends on how long ago as to how hard to find.
Also the stop forum spam is stock in version 7.5.7.
I thought you were using it. From a prior post you referenced some info that relates to it.
