Battle.net - Blizzard's online service that stores personal and financial data for players of games such as Diablo 3 and World of Warcraft - was recently hacked, the developer confirmed.
"This week, our security team found an unauthorised and illegal access into our internal network here at Blizzard," said Blizzard's president Mike Morhaime. "We quickly took steps to close off this access and began working with law enforcement and security experts to investigate what happened."
"At this time, we've found no evidence that financial information such as credit cards, billing addresses, or real names were compromised. Our investigation is ongoing, but so far nothing suggests that these pieces of information have been accessed."
So what has been compromised? A list of email addresses for global Battle.net users outside of China, while players from North America, Latin America, Australia, New Zealand, and Southeast Asia who use North American servers may have had the answers to their personal security questions and information relating to mobile and dial-in authenticators leaked.
"Based on what we currently know, this information alone is NOT enough for anyone to gain access to Battle.net accounts," Morhaime emphasized.
The cryptographically scrambled versions of Battle.net passwords were also stolen from those using North American servers, but Morhaime explained that has little likelihood of revealing anyone's real password. "We use Secure Remote Password protocol (SRP) to protect these passwords, which is designed to make it extremely difficult to extract the actual password, and also means that each password would have to be deciphered individually."
Still, he sugggested players on North American servers play it safe. "We recommend that players on North American servers change their password... Moreover, if you have used the same or similar passwords for other purposes, you may want to consider changing those passwords as well."
Morhaime noted that soon players on North American servers will automatically be prompted to change their password and security questions and mobile authenticator users will be asked to update their software. He also said that Blizzard e-mails never ask users for their passwords, so beware of any phishing e-mails with that sort of unusual request.
"We take the security of your personal information very seriously, and we are truly sorry that this has happened."