To be fair, boards like invision and phbb are not 'hackable' as you put it. The way in is through guessing the password of a super mod or the administrator. And to be fair, in cetain cases, thats not hard!

The way to do find out a little about who did the damage would be to go thru the moderator logs (or admin logs) and look at the IP address given where said damage has been caused. Due to the likes of Norton and other security set-ups now tho, IP's are changed all the time and pointed all over the world for 'security reasons' so that may not help anyway.

The person who did the damage would also have background knowledge of the Admin Panels. Hence how they knew where to go to change others' passwords etc. Your standard tom, dick or harry wouldnt know where to go so quickly! So maybe they are from a moderation team of a different site... or at worst, an admin. Jealousy is a bad thing!

If any posts/threads were deleted, hopefully the site admins created a recycle bin and hid it away from moderators eyes. Root Admin should be able to rectify all problems by restoring everything. If this isn't the case then unfortunately they are gone forever and they will have to start again.

Asking the servers for hlp will just get you a "Sorry sir, because this issue is based within a software package on our server there is nothing we can do". Thats even if they know what a forum software is!!!

Only true way of sorting it is to get Root Admin signed in, change all the moderation team passwords into mixed numerics (over 26 letters/numbers long) and then start tidying up and sorting out the mess from there. The reason for 26+ characters is that some 'hackers' use a tool that fifures out passwords... unfortunate for them tho as after 26 characters, the tool has to start again and again due to being too many to figure out.

Not much more to say on the matter mate. They just need to learn from this and move on. Changing passwords and choosing staff wisely is the next step.

Hope that helps you/your mate out