The account details of millions of online gamers have been stolen in a hack attack on games company Blizzard . The company , which makes the World Of Warcraft , StarCraft and Diablo franchises posted a message on its website today advising players using North American servers to change their passwords for the account management service . The compromised data relates to Battle.net accounts which are used for all of Blizzard 's games . In a posting today the company said : This week , our security team found an unauthorized and illegal access into our internal network here at Blizzard . We quickly took steps to close off this access and began working with law enforcement and security experts to investigate what happened . The post goes on to explain that the data that was illegally accessed included a list of email addresses for global Battle.net users outside of China . Players on North America servers ( which includes users in North America , Latin America , Australia , New Zealand and Southeast Asia ) , had their security question details hacked as well as information relating to Mobile and Dial - In authentication . Cryptographically scrambled Battle.net passwords were also taken . The company has advised that gamers that play online via North American servers should change their passwords as a precaution . The company has stressed it would be extremely difficult to access actual passwords using the scrambled data stolen . They also stressed that no financial data had been accessed , such as credit cards or billing addresses . Blizzard said that users should be aware of any potential phishing scams that may follow as a consequence of email details being out in the open . Blizzard Entertainment boss Mike Morhaime said the hack had been discovered on August 4th , and that the company were : truly sorry that this has happened . The company said it had spent the time since August 4th fixing the vulnerability in their systems and finding out what information had been compromised . Following the hack the company is likely to face criticism over its decision to make games that require a login via Battle.net and can not be played offline . Despite the loss of passwords and email data Blizzard 's use of a Secure Remote Password protocol is likely to have minimised the consequences for users as the system makes it near impossible to brute - force a password , a method hackers use in which a computer attempts every possible key or password until it succeeds . ;