Agentdoc.b is a trojan that drops malicious files on the infected computer. Once executed, the parasite opens a Microsoft Word document, which is written in Japanese, and installs itself to the system. It also installs a rootkit and a keylogger, which logs all user keystrokes. Gathered data is stored locally on the compromised computer. Agentdoc.b uses a rootkit to hide its files and registry entries, and therefore avoid detection. The trojan also attempts to download from the Internet and execute other malicious files. Agentdoc.b runs as a service on every Windows startup.