Valve co-founder and managing director Gabe Newell has confirmed the details of last November's cyber attacks on the Steam distribution service, revealing encrypted credit card information had been compromised.
"Recently we learned that it is probable that the intruders obtained a copy of a backup file with information about Steam transactions between 2004 and 2008," he said.
"This backup file contained user names, email addresses, encrypted billing addresses and encrypted credit card information. It did not include Steam passwords."
At this time Valve do not believe any of that information has been accessed, but advised users to be vigilant.
At the time of the hacking, Newell wrote to Steam users to say, to Valve's knowledge, no encrypted data had been taken.
"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," read a statement from Newell.
In an unconnected incident, yesterday Steam was down for a full 80 minutes in a power outage, after problems at one of the company's data centres.
"Our data centre's uninterruptible power supplies experienced a power failure," reported the official support forum last night.
"The power is back on now and we're working to get service restored as quickly as possible. We apologize for any inconvenience this may have caused."
In January Valve's latest financial statements showed the service saw more than a 100 per cent increase in year-over-year unit sales for the seventh year running.