Well VAC did an update recently making vac disabling impossible cause unless VAC is detected running with your game you get kicked. So you can only play using the ban bypasser function that the tool provides, think you can play public matchs as well doing that.
vac-ban bypass, that's not possible.
this is "probably" a trojan.
You should research before you say its a virus. This is the old version of vac chaos. The new one you need to use the vac ban bypass option to play because steam was updated so that unless vac is detected to be running then you will be kicked for steam connect failed. When using the ban bypass option you can start the game so you don't get the error and then host a ranked lobby using the hosting tool built in. Since you are host you can't be kicked since the games programmed like that, its the same with cod4 and cod5, if your punkbuster isnt up 2 when ur hosting a game it trys 2 kick you but if u look in console it says cannot kick host.
None of this is a virus but i would suggest not downloading the attachment and searching for vac chaos on google but make you go 2 the offical site.
Also paladin im an extremely trusted member, i would never post a virus.
I got banned by this, it'll only extend bans (For quite a while).
I've been using this for at least 6 months and i've only been banned once when the game crashed saying vac was detected, but that was on an older version of vac chaos. Not been banned since then, only thing that happens is you get flagged by iwnet and it just won't let you find games or anything so u need to reset your stats with EAM.