Perfwo is a trojan that steals login names, passwords, character details and other confidential user information used in the Perfect World online computer game. Gathered data is transferred to a predetermined web server or sent to a predefined e-mail address. The trojan terminates some running antiviruses and security-related programs. It also injects malicious code into legitimate processes in order to record user keystrokes and hide its presence in the system. Perfwo secretly runs on every Windows startup.