It seems someone burst S2’s bubble yet again and got his hands on the whole of Heroes of Newerth’s user account database which includes the gamers’ logins, e-mails and passwords and all the other personal information they’ve used to paid for items in the past (if indeed they have).
If you use your HoN password on any other online service chances are that the hacker will eventually gain access to those websites as well so you’re better off browsing through your browser’s saved password cache, finding out exactly where you’ve used that password and changing it immediately. I’ve tried searching for the actual text dump of the password files online (because I definitely don’t like to see my personal information spread all across the web) but so far I’ve been unable to find it so I’m hoping that the hacker at least keeps it to himself.
HoN’s servers were pulled offline while S2 tries to patch their faulty security which has been proven weak in the past when a series of denial of service attacks maybe half a year ago flooded the servers eventually making it impossible for players to access the service.
Someone named Ryan_HTP on Reddit made a post claiming authorship for the attack and you can see his answers to comments being made on his thread here. We’ll keep a close eye on this situation as it develops and provide you with updated information as it arrives.
EDIT: I’ve just logged into the server and got prompted to update the game to a new version (18.104.22.168) and after updating managed to login successfully although matchmaking is still down. Hopefully all security breaches have been fixed but honestly I wouldn’t count on that so be sure not to use your HoN password for anything else… ever.