Yep, that's what I expected. That is obsolete and you really should upgrade to at least 4.0.4.
https://vborg.vbsupport.ru/showthread.php?t=74961
or the latest mutigarage.
https://vborg.vbsupport.ru/showthread.php?t=76163
If you are going to stay on 3.1.1 then you need to find and install the vbulletin 3.0.5 updates in the vbgarage 3.1.1 thread. There is a huge link to it in the hack announcement.