Valve's Steam distribution-cum-social-gaming platform receives adulation from most PC gamers, but its security track record could be better. Last year, Steam servers were hacked, and an encrypted database containing user information was leaked. Now, security site The H reports that Steam is vulnerable to a zero-day exploit.
The problem lies with steam:// URLs, which the Steam client app registers upon installation. You can see steam:// links all over the Steam store; they usually open up the client to a specific page, but according to The H, they can also be used to open games and connect to multiplayer servers.
In the simplest case, an attacker can use [the URL protocol] to interfere with the parameters that are submitted to the program. For example, the Source engine's command line allows users to select a specific log file and add items to it. The ReVuln researchers say that they successfully used this attack vector to infect a system via a batch file that they had created in the autostart folder. Popular games such as Half-Life 2 and Team Fortress 2 use the Source engine and are distributed through Valve's Steam platform. In the even more popular Unreal engine, the researchers also found a way to inject and execute arbitrary code. Potential attackers would, of course, first have to establish which games are installed on the target computer.
Until Valve can address the vulnerability, the H recommends that folks game on a "dedicated gaming PC on a separate network." Failing that, installing a copy of Windows on a separate partition and keeping your games there provides some measure of safety.