Security Experts:

Cybercriminals Target Steam Users with New Trojan

Many users of Steam, Valve’s online gaming platform, have complained over the past few weeks about game items getting stolen, and the culprit appears to be a new piece of malware.

According to Doctor Web, the attackers use Steam chat and forums to lure their victims by sending messages claiming that they want to trade various items. The “image” files attached to these messages, which show the items allegedly being traded, hide a piece of malware detected by the Russia-based security firm as Trojan.SteamBurglar.1.

Once it’s executed, the Trojan targets the steam.exe process and extracts information on game items, Dr. Web said.  Then, the items are transferred to an account owned by the attacker. The threat is designed to look for key words such as “legendary,” “immortal” and “rare” to make sure that the stolen items are valuable.

A similar (possibly the exact same) piece of malware has been analyzed by a researcher at F-Secure who has uncovered a slightly different attack vector. The cybercriminals have been using bots on the Amazon-owned gaming video platform and community Twitch to advertise so-called raffles in which users can win “Counter Strike: Global Offensive” items.

Victims are first asked to click on a link which takes them to a Java application that requests names, email addresses, and permission to publish users’ names in case they win the raffle. In the background, a piece of malware dubbed “Eskimo” by F-Secure is dropped onto the user’s computer.

The malware is capable of taking screenshots, adding new friends in Steam, accepting friend requests on the user’s behalf, initiating item trades, purchasing items, sending trade offers, and even selling items on the Steam Community Market. In order to get rid of stolen items quickly, the attackers sell them at discount rates of 12% and even 35%, the security company said.

“Being able to sell uninteresting items will allow the attacker to gather enough money to buy items that he deems interesting. The interesting items are then traded to an account possibly maintained by the attacker,” F-Secure said in a blog post.

Users’ accounts are protected against takeovers by Steam Guard, a security feature that’s enabled by default. Steam Guard requests a special access code sent to the user via email in case a login attempt from an unrecognized device is detected. However, in this case, Steam Guard can’t protect the accounts because the malicious activity takes place from the user’s own computer.

F-Secure experts suggest that such pieces of malware can be neutralized by adding another security check that’s designed to look for several items being traded to a newly added friend, or item sales on the Steam market at very low prices.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.