False-positive detections
Those that have been caught by the system also criticise it, usually with the claim that it has made a false positive. The only recorded instances of false positive have been under VAC1:
* Immediately after VAC's release, memory corruption (corruption of the physical memory used by the game modules caused by bad RAM or misbehaving processes) would lead to a VAC ban.[citation needed] When this problem came to light, VAC was altered so that corrupted memory would only lead to a drop from the server and all bans due to this were reversed.
* In 2002, joining secure servers while running under the WineX Windows emulator for Linux led to a VAC1 ban.[citation needed] The bans were shortly reversed and the issue reduced to WineX players merely being kicked from secure servers, but the incompatibility was only fully resolved — allowing Linux players to connect to VAC-protected servers — a year later.[6]
* During the early stages of VAC1's life, detections were generic enough to allow non-cheat applications to trigger a ban if they behaved in similar ways to cheats or contained similar code. This led to bans triggered by acts other than cheating. In 2003 the problem came to light when players were banned for using HLamp, which allowed playing MP3s by integrating with Winamp.[7] The mistake and its effects were reverted within five hours of the first HLamp users receiving their bans, and VAC's detection methods were made a lot less generic as a result. Furthermore, every existing VAC ban was removed in order to account for players banned due to other, unknown, non-cheat programs.[citation needed]
* An apparent server-side glitch on 1 April 2004 led to a glut of arbitrary VAC1 bans. All were reverted within an hour of the problem arising.[8] However, because of the dubious nature of the date of this occurrence, it is possible it was simply a prank.
VAC2's presumed hash detection methods continue to make false positives such as these extremely improbable, and slow the detection process by requiring cheats to be individually identified.[citation needed]
Hacks may also be hidden inside otherwise legitimate mod or skin downloads that are created to maliciously get innocent people permanently banned.fuente:
http://en.wikipedia.org/wiki/Valve_Anti-Cheat