I don't know what the reasons for trying to "hack" our Forum. They can be vast and numerous. It can be the guy down the street to someone in a foreign land. It may be a focused attack or someone trying it for fun.
As you may know, I screen every membership application. I can definitely tell you, that OCC sees on a weekly basis, hackers, spammers, and bogus applications. I have a "filter" in place that removes 99% of known spammers, but some always manage get through.
So, between our IT Server Guy and myself, we try and do our best to keep that crap out.