Company tries to thwart cheat developers by making it financially unfeasible

In response to a Reddit thread claiming that the Valve Anti-Cheat (VAC) program records users’ browsing history, Valve co-founder Gabe Newell replied that it isn’t the case. Newell broached the subject on his own Reddit thread to provide an explanation of how VAC works in order to refute these claims.

Newell brought up the topic of cheat developers who, according to Newell, have difficulty in getting users to pay them. This has resulted in cheat developers programming DRM and anti-cheat codes for their product creations in order to get paid. To do this, however, the cheat program will send out a call to a DRM server in order to authenticate whether or not it was actually paid for.

What VAC does, Newell said, is check “for the presence of such cheats.” He explained, “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.”
For Valve, trust is an important part of the multiplayer community and, according to Newell, “Cheat versus trust is an ongoing cat-and-mouse game. New cheats are created all the time, detected, banned, and tweaked. This specific VAC test for this specific round of cheats was effective for 13 days, which is fairly typical. It is now no longer active as the cheat providers have worked around it by manipulating the DNS cache of their customers' client machines.”

Because kernel-level cheats are expensive to create, Valve’s goal, Newell said, “is to make them (cheats) more expensive for cheaters and cheat creators than the economic benefits they can reasonably expect to gain.”

Newell went on to explain that the accusations made against Valve are a form of attack from cheat developers hoping to cause mistrust between Valve and its consumers. He ended his post saying, “Our response is to make it clear what we were actually doing and why with enough transparency that people can make their own judgments as to whether or not we are trustworthy.”