Gamers are being warned that a dangerous newly discovered trojan virus downloader is being bundled with popular online games downloaded from other sites.

Dubbed “Joao” by researchers at security firm ESET spol. s r.o, the trojan was found in the wild bundled with versions of online role-playing games from Aeria Games, including the massively multiplayer online role-playing game Grand Fantasia on a site identified as Ignitgames.

Malware is nothing new, but the researchers are ringing the alarm bell with Joao due to the potential harm it can cause a victim’s computer. One installed with the game, Joao can download multiple malicious modules, including those facilitating remote access, espionage and distributed denial-of-service attacks. Worse still, Joao itself is barely detectable, running silently in the background while the downloaded game plays without any user disruption or signs of malicious activity.

The trojan has been detected in games offered by other sites, but in some cases those sites have gone offline or Joao has disappeared from the games being offered. That suggests that not all third-party sites were intentionally spreading it, since they might not have known it was there.

The researchers noted that if users have downloaded various games from different sources and are concerned about infection, they should run a search for “mskdbe.dll,” the main file utilized by Joao. If the result comes back positive, “your computer has most likely been infected with the Joao malware,” they added.

The other advice, which can never be repeated enough, is that users should practice safe Internet. In this case, they should download games only from the original site. Although Joao is not currently detected by all antivirus packages, it should soon be, meaning it’s always important to be running up-to-date antivirus software.

Image: Aeria Games