Fighting malware and spam

Worm

Malware that spreads itself across networks

Worms are a form of self-replicating malware which spread by placing copies of themselves in email attachments or instant messages, in shared folders or on visible network shares, or via backdoors or vulnerabilities in network-exposed software. As well as spreading, and using up valuable bandwidth in the process, worms often open further backdoors, disable security software and install bot software to add infected systems to zombie networks.

Worms have caused many of the biggest and highest-profile outbreaks in the history of malicious code, including the infamous Melissa and Loveletter incidents in the 1990s and SQL/Slammer in 2003.