Steam's VAC protection now scans and transfers your DNS cache
I think we can all agree that games need some form of cheat protection. This is especially true for multiplayer games where people compete against each other.
If you have ever been on a server where a cheater ruined the game for everybody else on the server by using aimbots or speed hacks, you know that this needs to be prevented from happening.
Many gaming companies use anti-cheat software, either their own products or third-party products such as Punkbuster.
If you have played any Valve games on Steam, you know that the company uses its own Valve Anti-Cheat (VAC) solution since 2002 when it was introduced to Counter-Strike 1.6.
According to Wikipedia, more than 60 games use VAC on Steam. This includes all first-party Valve titles but also popular games such as several Call of Duty titles, Killing Floor, Dead Island, DayZ or Resident Evil.
A ban does not take effect immediately, but after a random time in days or even weeks. If an account is flagged as cheating, it will be blocked from any games that use VAC for protection.
Update: According to a Gabe Newell, Valve is not sending the browsing history to Valve.
A recent thread on Reddit indicates that VAC has been modified by Valve recently to scan a computer's DNS cache next to all the other protection forms that it utilizes.
The DNS cache is a system-wide cache that records any domain name look-ups on your machine. If you visit a site like Ghacks or Facebook, then access to those sites is stored in the cache.
All programs make use of the cache, which means that all of your Internet activities are recorded by it, even those where you never visit the site in question thanks to technologies such as Chrome's network actions prediction feature.
According to the thread author, VAC is retrieving the cache information and submits hashed versions of each domain you have visited or was looked up to remote servers. Hashed means it does not know the url itself, but only a hash of it.
While it is not clear what happens then, it is likely that the hashes are compared against a database of known cheating services and websites.
We do not know if users will be banned outright if domains are found in the cache that are known cheating sites, but think that it is unlikely that this is going to happen. It is more likely that a "suspicious" flag is added to the account, but we do not know that for sure either.
Clearing the cache before you connect to Steam offers the best form of protection against this.
- Use Windows-R to bring up the run box, type cmd, and hit the enter key.
- Type ipconfig /displaydns to display the current cache status.
- Type ipconfig /flushdns to empty the cache.
You can automate the process if you like. The following batch file clears the DNS cache and loads Steam as the second command.
cd C:\Program Files (x86)\Steam
Note that you may need to alter the third line that switches to the Steam program directory if you have installed or moved Steam to another directory.
Create a new text document, paste the contents into it, and save it as Steam.bat or similar. Make sure .bat is the file extension, and not .bat.txt.
You start Steam by running the batch file instead of Steam directly.
Alternatively, disable the DNS Cache service on your system. This may slow down look ups somewhat for sites that you visit regularly though.
- Press Windows-r, type services.msc and hit enter.
- Locate the DNS Client service, right-click it and select Stop.
- Double-click it and set the startup type to manual.
Valve has not commented yet no this, and the information have not been verified by third-parties. You should take the information with a grain of salt until it has been verified or debunked.Advertisement