I don't know if anyone has tried to get into my account, but then again, I never connected my email with the NIWA forums.
As long as you keep a secure password, then the hacker(s) won't be able to succeed unless he/she/they do some sort of mega server hack or something, which can only be accessed by a select few. Considering the hacker(s) are trying multiple logins, with repeated fails, it can be more or less safe to say that a secure password is all that is required for the member-in-question.
The staff is going further, however, working to solve the issue. So, you should be getting less emails like this soon enough.