Timeserv is a rapidly spreading Internet worm that spreads by e-mail through messages with infected executable attachments. Timeserv letters trick the user into believing that they have been sent by Microsoft Customer Support. Once executed, the parasite installs itself to the system and runs a spreading routine. It sends bogus e-mail messages to all the contacts in the Windows Address Book. The worm’s payload is quite dangerous. Timeserv opens a back door providing the attacker with unauthorized remote access to the compromised computer. The intruder can manage the system and steal user sensitive information. The parasite also injects malicious code into legitimate system processes. This may cause the infected system to crash and restart without asking for user permission. Timeserv runs on every Windows startup.