Earlier this week it came to our attention that Valve’s video game digital download service, Steam, had suffered an intrusion on its user forums—it has now come to our attention, via a message sent from Valve Corporation head Gabe Newell that states that credit card numbers and other personal information had been taken along with passwords and usernames during the website defacement.

Dear Steam Users and Steam Forum Users,

Our Steam forums were defaced on the evening of Sunday, November 6. We began investigating and found that the intrusion goes beyond the Steam forums.

We learned that intruders obtained access to a Steam database in addition to the forums. This database contained information including user names, hashed and salted passwords, game purchases, email addresses, billing addresses and encrypted credit card information. We do not have evidence that encrypted credit card numbers or personally identifying information were taken by the intruders, or that the protection on credit card numbers or passwords was cracked. We are still investigating.

We don’t have evidence of credit card misuse at this time. Nonetheless you should watch your credit card activity and statements closely.

While we only know of a few forum accounts that have been compromised, all forum users will be required to change their passwords the next time they login. If you have used your Steam forum password on other accounts you should change those passwords as well.

We do not know of any compromised Steam accounts, so we are not planning to force a change of Steam account passwords (which are separate from forum passwords). However, it wouldn’t be a bad idea to change that as well, especially if it is the same as your Steam forum account password.

We will reopen the forums as soon as we can.

I am truly sorry this happened, and I apologize for the inconvenience.

Gabe.

At the time of the initial defacement, it was believed that the user forums database and the service were separate and thus the attackers didn’t get the credit card information and addresses stored in the service. However, from this communication, it would appear that it didn’t save Steam from a deeper compromise.

Steam boasts over 35 million users–and some percentage of that are paying customers with credit card information stored in the service–this makes for a fairly noticeable breach–in comparison Sony’s PlayStation Network intrusion affected 77 million customers.

Fortunately, Newell claims that the credit card information has been encrypted so at least it’s not immediately available in the wild. However, it is suggested strongly that users keep a close eye on their statements; the state of encryption today is such that it is something of a deterrent, but like a lock on a door it will not stop a determined attacker. Given enough computational horsepower it could be a matter of hours or days before the credit card information is unlocked.

It is suggested that if you use Steam, you should change your password immediately and make certain that you have enabled two-factor authentication. Steam’s two-factor authentication requires that whenever a new computer runs their download client the person running it must also identify themselves with their e-mail account. Also: make certain you never use the same password on your e-mail address as you do with any account. In this fashion you will be able to reestablish your account via your e-mail address even if your account is compromised.