Valve denies transmitting users' DNS cache

February 18, 2014 // 10 a.m.

Tags: #cheat #cheating #dns-cache #gaben #gabe-newell #pc-gaming #privacy #reddit #security #vac #valve #valve-anti-cheating

Valve's Gabe Newell has spoken publicly to refute claims that his company's anti-cheating software, VAC, transmits a hashed list of all entries in a user's DNS cache - a complete history of all internet traffic from the past 24 hours, in other words - back to its servers for reasons unknown.

The accusations against Valve came as the result of a thread on social networking site Reddit in which users had reverse-engineered the VAC software and discovered that it created hashes for every entry in a user's DNS cache for reasons which appeared unclear. Some users went still further, claiming that this list of hashes was transmitted back to Valve's servers over an encrypted channel - giving the company a means of monitoring what its users are doing on the internet.

The DNS cache, active by default on Windows and configured to retain data for 24 hours, fills itself every time you look up a domain name - regardless of how that lookup is made. Clearing your history, or using a web browser's private browsing mode, provides no protection against monitoring of the DNS cache. Valve's use of the DNS cache, therefore, raised something of a privacy panic when it was discovered.

'We don't usually talk about VAC (our counter-hacking hacks), because it creates more opportunities for cheaters to attack the system (through writing code or social engineering). This time is going to be an exception,' Valve founder Gabe Newell explained in his response to the furore on Reddit.

'There are a number of kernel-level paid cheats that relate to this Reddit thread, claimed Newell. 'Cheat developers have a problem in getting cheaters to actually pay them for all the obvious reasons, so they start creating DRM and anti-cheat code for their cheats. These cheats phone home to a DRM server that confirms that a cheater has actually paid to use the cheat. VAC checked for the presence of these cheats. If they were detected VAC then checked to see which cheat DRM server was being contacted. This second check was done by looking for a partial match to those (non-web) cheat DRM servers in the DNS cache. If found, then hashes of the matching DNS entries were sent to the VAC servers. The match was double checked on our servers and then that client was marked for a future ban. Less than a tenth of one percent of clients triggered the second check. 570 cheaters are being banned as a result.

'Do we send your browsing history to Valve? No. Do we care what porn sites you visit? Oh, dear god, no. My brain just melted.
'

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