It appears someone has figured out how to hack Drupal (the backend software for SoR Member Tutorials).
They've managed to use a bot to repeatedly create accounts without Admin approval.
I haven't seen any damage or graffiti yet, but just keep an eye out for anything strange.
I don't know how to block it, I can only just manually delete accounts as they are created. And wait for a patch to come out . . .
sigh