San Francisco, Jul 28 (IANS): Players of an old Call of Duty game are being infected by hackers with a worm that automatically spreads in online lobbies.

On June 26, a player of Call of Duty: Modern Warfare 2 warned other players on a Steam forum that hackers "attack using hacked lobbies," and advised using an antivirus, reports TechCrunch.

It looks like the malware mentioned in the thread is on the malware online repository VirusTotal.

Another player claimed to have analysed the malware and said in the same forum thread that the malware seems to be a worm, based on a number of text strings inside the malware.

The presence of those strings in the malware, which suggests a worm, was confirmed by a game industry insider who asked to remain anonymous because they were prohibited from speaking to the press.

Neil Wood, spokesperson of Activision, which released the game in 2009, referenced a tweet posted by the company from the 'Call of Duty Updates' account on Thursday that indirectly mentioned the malware.

“Multiplayer for Call of Duty: Modern Warfare 2 (2009) on Steam was brought offline while we investigate reports of an issue,” the tweet read.

It is still unclear why the hackers are spreading this malware.

The malware is a worm since it seems to automatically spread from one infected gamer to another through online lobbies.

"This means the hackers must have found and are exploiting one or multiple bugs in the game to execute malicious code on the other players’ computers," the report said.