Gamers on the popular Steam gaming service have been targeted with phishing scams via the service’s popular Marketplace - with apparent ‘bargains’ offering a sting in the tail, according to CBR Online.

Gamers have been targeted with infected files via both Steams own Marketplace and trading sites such as CSGolounge.

The scam goes like this: a gamer will offer an in-game item for sale, and his victim will download an image file before purchase  - except instead of the image of the in-game weapon they expect, they install a screensaver, which contains a nasty Trojan.

Steam: Screensaver with sting in the tail

Victims report their accounts are stripped of in-game goods within seconds after installing the ‘screensaver’

One victim complained, ‘Hey, yesterday i started to trade through csgolounge, i had four items, p250 splash and M4A1-S guardian. Someone offered me a knife and sent me a picture link, it was saved as a screensaver. I opened it, and the next minute i checked my items they were gone.’

It’s not clear which malware is being used for the scam, but users are advised to contact Steam support, and to run a full AV scan on their PC, before changing their Steam password if they believe they have been infected.

Gamers have not reported effects other than the loss of in-game goods, but it's conceivable the malware could have other functions.

'Bargain' weapons are actually Trojans

Commenters on Steam’s forums warn that while Valve’s support staff may return items after a theft, they become markedly less helpful if a user reports repeated thefts.

One commenter said, ‘Why in the hell would you execute a Screensaver file from a total stranger? They are nothing more than an .EXE with another name. He wasn't a hacker, he was a phisher and you fell for it.’

A WeLiveSecurity guide to some of the common scams found in online games can be found here.