As a matter of interest, did this start around the 10th August?
I run a couple of small forums on
Enniskerry - Gateway to the Garden of Ireland and
Jack and Jill Childrens Foundation using SMF [I switched from phpBB because of hacking attempts].
Since the 10th I have been plagued with attempted postings for porn sites, dubious medical sites and the like. Most of the postings are coming from Russia [boom.ru, bk.ru, list.ru etc etc] and Egypt [gawab.com]. Every morning there is a new clutch of non-authenticated 'new members' which have to be cleared out and a new series of bans inserted.