The trojan, called PWSteal.Wowcraft, affects Microsoft Windows operating systems and injects msdll.dll code into certain processes before emailing the game's passwords back to the trojan's author. The malware also attempts to disable a number of processes, according to Symantec Security Response.
Malicious users often steal passwords from recreational programs in the hope that an affected user also employs that password for online financial transactions.
Less than three months ago, about 2,000 South Koreans had their names and national identity numbers stolen from the popular online role-playing game "Lineage" so hackers could play the game for free.
Video game creator White Wolf Publishing, the maker of "World of Darkness" role-playing games, had user data stolen from its website late last year.
The company told users via its website that it was the target of an international hacking attempt on Dec. 11, 2005, adding that the malicious users were able to exploit a flaw in the company's software and access data.