Valve Anti-Cheat

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Valve Anti-Cheat, abbreviated to VAC, is a proprietary anti-cheat solution developed and maintained by Valve Corporation as a component of the Steam platform.

VAC was first released with Counter-Strike 1.4 in 2002,^[1] 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.

VAC2 has been implemented in GoldSrc, Source, and Unreal Engine 2 titles, as well as Call of Duty: Modern Warfare 2. It is a part of Steamworks.

Contents 1 Advantages 2 Disadvantages 3 Successes 4 Delayed bans, criticism & rationale 4.1 False-positive detections 5 See also 6 References

[edit] Advantages

• 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,^{[citation needed]} again denying cheat producers information.

[edit] Disadvantages

• 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 (sv_pure) that prevent custom content from overwriting the game's defaults was created to alleviate this.^[2]

[edit] Successes

On November 17, 2006, Valve announced that "new [VAC] technology" had caught "over 10,000" cheating attempts in the preceding week alone,^[3] the first real indication of the scale of anti-cheat operations. It should be noted that not all of the accounts banned would have contained legitimate, purchased games, and also that there is no external audit on the figure.

[edit] Delayed bans, criticism & rationale

If a cheat is found the player's Steam account will be flagged as cheating immediately, but the player will not receive any indication of the detection. It is only after a delay of "days or even weeks"^[4] that the account is permanently banned from "VAC Secure" servers^[5] for that game, along with other games that use the same engine. (e.g. Valve's Source games, GoldSrc games, Unreal engine games).

[edit] False-positive detections

Some who are banned by VAC claim that it has made a false positive. Here a distinction must be made between false positives caused by incorrect detection, and grey-area false positives caused by correctly-identified code modifications which do not actually offer an unfair advantage.

• There are three recorded instances of incorrect detections, all under VAC1 and all quickly rescinded. These were:
  1. On its initial release, VAC would issue bans for faulty memory. Valve quickly updated VAC to only kick for faulty memory^[6] and reversed all bans for faulty memory.
  2. The effect of running the VAC-protected game through the WineX software compatibility layer for Linux.^[7]
  3. An apparent server-side glitch on April 1, 2004.^[8]
• There are four recorded instances of the "benign cheats" described above triggering bans. These are:
  1. VAC1: HLamp, which allowed the user to control Winamp from the game's interface. Detection later reversed, and all bans caused by it rescinded.
  2. VAC2: The X-Spectate tool, which allowed server administrators to enable a wallhack effect while spectating to help decide if another player was doing the same. Later downgraded to a kick from the server, but bans not rescinded.
  3. VAC2: The single-player Half-Life modification Paranoia, which made changes to the engine's renderer that propagated to multi-player games.^[9] This still triggers a ban and no bans caused by it have been reversed.
  4. VAC2: sXe Injected, an anti-cheat system for Counter-Strike, triggers a VAC ban.^{[citation needed]}

Cheats may be hidden inside otherwise legitimate mod or skin downloads that are created to maliciously get innocent people banned. Since the source of a cheat installed on a computer cannot be proven, bans due to this are never rescinded.^[4]

[edit] See also

• Cheating in online games
• DMW Anticheat
• PunkBuster
• Steam (content delivery)
• Warden (software)

[edit] References

v • d • e Video game technology by the Valve Corporation Content delivery Steam  · Steamworks Game engines GoldSrc  · Source Third-party modifications GoldSrc modifications  · Source modifications Other topics Half-Life TV  · Source Software Development Kit  · Valve Anti-Cheat