The Trojan-PSW:W32/OnlineGames family is quite large. Variants in this family are designed to steal confidential information from players of popular online games, such as World of Warcraft.
Onlinegame password stealing trojans are designed to steal account information in order to allow a remote hacker access to the player's account. The hacker can then logon and steal the player's virtual assets by transferring them to another player account. Such assets are often sold or auctioned off for real-world currency. With millions of players, such trojans can easily affect thousands of users.
Usually OnlineGames trojans are spammed in e-mails with deceptive and enticing subjects and attachment names. However, such trojans can also be downloaded by other malicious programs, for example by worms, backdoors, and trojan downloaders.
After the trojan's file is started by a user, it installs itself to the system by copying its file to Windows folder. It also creates a startup key value in the Registry for the copied file. This is done to make sure that the trojan's file is started every time Windows boots. The startup key value is created under the following Registry key:
After installation the trojan locates the Explorer.exe process, drops a DLL from its body onto a hard drive and injects the dropped DLL into the Windows Explorer process. Note that unlike the main trojan's file, the DLL is dropped into the Windows System folder. The dropped DLL is the main spying component.
In order to retrieve sensitive data, the trojan reads the process memory of certain game executables, for example WOW.EXE (World of Warcraft), ElementClient.exe (Perfect World), CabalMain.exe (Cabal Online). The trojan may also attempt to read certain variables from the games' configuration files. For example, the current game server address may be read from the CurrentServer.ini file. Some variants of the trojan have keylogging capabilities. They monitor what keys a user pressed and sends the keyboard activity logs to a malicious hacker.
The spying component contains an encrypted URL that is used to send stolen data. The stolen data is sent to a hacker by accessing the specified website with a specially constructed URL.
The trojan can also try to connect to a hard-coded IP Address, create a socket and send stolen data to it. Typically many of these IP addresses are registered in China.
Some variants try to suppress AVP anti-virus scanner windows. Also, if a system debugger is detected, the trojan does not attempt to steal data. Some of trojan's strings are formed by executable code. This is done to make the trojans less "visible" to heuristic scanners that react on certain types of text strings in the inspected files.