Forbidden registration bypass?

Hey everybody. So a hacker tried to mess out with our forum (luckily it didn't go too well for them), firstly via XSS, secondly - i don't know how, but they manage to register, even when the registrations are forbidden by administrators and the subscriptions are only allowed when they are approved by administrators. We do have an HTML enabled on our forum but it's important, so is there any way to prevent them from keep making new accounds?

Hello,

May you eloborate more on how they are hackers? Did they try to get into any administrators accounts. I assume you have the setting ticked to forbid new registration? If so, try un ticking it then re ticking it and save, this might reset the setting on the server. You can also try ip banning the person.

Regards,
-Brandon