Trojans used to create botnets have long been implicated in spam and credit card fraud rings. But online games, particulary MMORPGs (Massive Multi-player Online Role Playing Games), are also a frequent target. Keylogging Trojans can be used to capture the login credentials for popular games and those accounts exploited for profit. Commonly, the attackers login to the stolen accounts and steal the in-game currency, rare items, and coveted equips, later auctioning them on IRC or eBay for real world money.
Keylogging Trojans are often embedded in botting programs - applications that play the in-game character for you, gaining levels and items even while you sleep. Botters are generally despised; not only are the players cheating their way into higher levels, the items gained in the practice can wreak havoc on the MMORPG economies. The silver lining, perhaps, is that these botters are likely to later find their characters divested of all their ill-gained goods, or banned from the game entirely.
Other Trojaned apps commonly include packet editors, zeny/gold generators, and item duplicators. Blizzard Entertainment, makers of WoW, Diablo, and StarCraft, warn battle.net users of the dangers of Battle.net Hack Programs, cautioning that "a very large number of programs advertised as Battle.net hack programs are actually 'Trojan' programs. Blizzard also notes that, "When a player who is secretly using your CD key is banned from Battle.net, the end result is that you end up being banned as well, because the corrective action was ultimately taken against the CD key and all accounts tied to that key."
Of course, not all the account thefts rely on technology to do the dirty deed; low-tech, socially engineered tactics are also employed. One website promises to deliver zeny to Ragnarok player accounts, alleging that a 'bug in the server code' makes it all possible. In reality, the website is nothing more than an HTML form with a POST action to send the submitted account info to an email address.
Other social engineering tactics rely on the naivete of new players (noobs or newbies), convincing them to divulge their account details with a promise to outfit them with new gears, gold, or zeny, or help them power level. A Ragnarok guild site for the popular Ragnarok Online game describes many of the pitfalls of iRO hacks. The advice is equally relevant to players of other MMORPGs.
To avoid being the victim of an MMORPG hijacking, never give your account details out to anyone - including people in-game who claim to be GMs. Never download packet editors, zeny generators, item duplicators, or botting programs. And don't support the Trojan creators either - don't buy auctioned zeny, gold, or MMORPG equipment to try to get ahead in the game. Your gain may well be at another's expense.
If you suspect a program you have downloaded may be a Trojan, submit it to these online scanners for a quick check. But remember, even if the online scanner gives the file a clean bill of health, that doesn't mean it's Trojan-free. It just means the scanner does not detect a Trojan it already knows about. The file may still be infected with a new or previously unseen Trojan. Your best line of defense is to play a legit game, bypass the cheats, and use common sense to avoid being scammed.