Valve Anti-Cheat


VAC was first released with Counter-Strike 1.4 in 2002, following Valve's decision to forego PunkBuster in preference of a proprietary system. The initial version, VAC1, saw success for a period, but in March or April 2004 updates ran dry as the Valve engineers maintaining it moved on to the production of its successor, VAC2. VAC1 swiftly became virtually useless during this period of development, but since its June 20, 2005, launch VAC2 has successfully overseen a decline in the number of cheating players across games protected by it.[citation needed]
VAC2 has been implemented in GoldSrcSource, and Unreal Engine 2 titles, as well as Call of Duty: Modern Warfare 2Shattered Horizon and Lost Planet: Extreme Condition. It is a part of Steamworks.
On November 17, 2006, Valve announced that "new [VAC] technology" had caught "over 10,000" cheating attempts in the preceding week alone, the first real indication of the scale of anti-cheat operations. Not all of the accounts banned would have contained legitimate, purchased games, and also that there is no external audit on the figure.
As of 2010, unofficial sources estimate that over a million Steam accounts have been banned by the VAC system.


  • Total integration through Steam, including using the Steam framework for any update tasks
  • Delayed bans deny cheat producers accurate and timely information
  • As of VAC2, client-side updates are not always required to detect new cheats, again denying cheat producers information.


  • Delayed bans (see below) means that cheaters are free to disrupt other players until their ban takes effect.
    • This may entice others to cheat, taking an "if they can do it so can I" attitude.
    • The burden of banning individual cheaters who have been detected by VAC but not yet banned remains on server administrators.
    • This also leads to the skewing of statistics and ranking systems, even if the cheaters' data is removed when they are banned.
  • VAC cannot detect 'content hacks', where, for example, texture transparency and color are manipulated, since they do not involve modification of any program code. In the Source engine the option to create "pure" servers that prevent custom content from overwriting the game's defaults was created to alleviate this.