(also worm virus)
Computer worm definition
A computer worm is a type of malware that replicates — spreads copies of itself — from computer to computer. A computer worm can multiply without human interaction and may cause damage without attaching itself to a software program.
Types of computer worms
- Internet worm. Some worms target popular websites with insufficient security. They attempt to infect the site and then infect a device accessing the website.
- Email worm. Email worms spread by creating and sending messages to all the addresses in the victim’s contact list. The messages include a malicious attachment that infects the new system once opened.
- File-sharing worm. These worms are disguised as media files and typically target industrial environments, such as water supply services, power utilities, and sewage plants.
- Cryptoworm. This worm encrypts data on the victim’s system and is used in ransomware attacks. The attacker usually demands payment in exchange for decrypting their files.
- Instant messaging worm. Like email, instant messaging worms are usually masked by links and attachments. The worm spreads by sending messages to the infected victim’s contact list.
How to tell if your computer has a worm
- Monitor your hard drive space. When worms replicate themselves, they start using up the free space on your hard drive.
- Keep an eye on speed and performance. Worms eat up your processing power, so they may slow down your machine and make programs crash or not run properly.
- Missing or new files. A computer worm may delete or replace files on a computer.