A worm, like a virus, is programmed to spread from one computer to another, but it does so without any user interaction. Worms do not need to travel through a "host" program or file. They can travel alone and replicate themselves in great volume. Worms slow down networks.
The term 'worm' was taken from a science fiction novel called, The Shockwave Rider, by John Brunner. When the researchers noted the similarities between this form of malicious software and the program described by Brunner, they adopted the name.
Deterring Worms
Detoxifying malware
Malware in the real world
A worm generally spreads without user action or a “host” program or file. It spreads by exploiting a flaw in popular software code or taking control of features on the computer that can transport files or information. Worms replicate in great volume and can consume memory or network bandwidth, causing a computer to slow down or stop responding.
A worm does this by sending out copies of itself to everyone listed in a person’s e-mail address book, and their computers would then do the same, causing a domino effect of heavy network traffic. Thus, worms sometimes cause the loading of certain web sites to be pain stakingly slow. A worm can also, enable someone else to access your computer from a remote location.
The possible ways of entry of a worm is similar to that of a virus:
- Email attachments
- Some of your email messages may contain attachments that are infected with worms.
- Shared network files and network traffic
- These network files may again be infected.
- World Wide Web (WWW) sites
- Some malicious websites contain worms that are downloaded automatically into your computer, using flaws in your Internet browser.
- File downloads from the internet
- Shared Floppy disks, CD-ROMS and ZIP Drives
- A worm can also enter your system when you transfer infected files from one computer to another.
- Pirated software
- Certain pirated software may cripple your computer due to certain malicious programs that comes bundled with the software.
However, many of the dangerous worms primarily spread through e-mail attachments.
Reference
Computer worm
http://en.wikipedia.org/wiki/Computer_worm
Computer worms information
http://virusall.com/worms.html