Valve has now issued an apology for the user privacy leak of information on Steam. Which took place prior to Christmas with an explanation of what actually happened. This issue affected approximately 34,000 users, the result of a caching error through a denial of service attack on Steam.
“Early Christmas morning (Pacific Standard Time), the Steam Store was the target of a DoS attack which prevented the serving of store pages to users. Attacks against the Steam Store, and Steam in general, are a regular occurrence that Valve handles both directly and with the help of partner companies, and typically do not impact Steam users. During the Christmas attack, traffic to the Steam store increased 2000% over the average traffic during the Steam Sale.
In response to this specific attack, caching rules managed by a Steam web caching partner were deployed in order to both minimize the impact on Steam Store servers and continue to route legitimate user traffic. During the second wave of this attack, a second caching configuration was deployed that incorrectly cached web traffic for authenticated users. This configuration error resulted in some users seeing Steam Store responses which were generated for other users. Incorrect Store responses varied from users seeing the front page of the Store displayed in the wrong language, to seeing the account page of another user.
Once this error was identified, the Steam Store was shut down and a new caching configuration was deployed. The Steam Store remained down until we had reviewed all caching configurations, and we received confirmation that the latest configurations had been deployed to all partner servers and that all cached data on edge servers had been purged.”
This leaked information varied, showing a users’ billing address, the last four digits of Steam Guard phone numbers, purchase history, the last two digits of credit card numbers, and sometimes an email addresses too.
“Full credit card numbers, user passwords, or enough data to allow logging in as or completing a transaction as another user,” a kindly re-assurance stated by Valve. So users who were not browsing the Steam store during that specific time frame were not affected.
Valve is continuing to work with the involved web caching partner to identify any users impacted by the leak in hope to improve its processes to ensure this does not happen again. “We apologize to everyone whose personal information was exposed by this error, and for interruption of Steam Store service.”