“A computer worm is a program which copies itself across a network.A computer worm differs from a computer virus in that a computer worm can run itself. A virus needs a host program to run, and the virus code runs as part of the host program. A computer worm can spread without a host program, although some modern computer worms also use files to hide inside.

Well known examples of the computer worm

The original computer worm was (perhaps accidentally) unleashed on the Internet by Robert Tappan Morris in 1988. The Internet Worm used sendmail, fingerd, and rsh/rexec to spread itself across the Internet. (more…)

Facts and Myths about Computer Viruses
—Technology Training Center—

When dealing with computer viruses, it’s important to remember that they are software. That means:

• Viruses can do anything other software can do:
• Viruses can delete files.
• Viruses can format hard drives or scramble the data on them.
• Viruses could (in theory) communicate over a network.
• Viruses cannot do anything impossible for other software
• Viruses cannot damage your CPU.
• Viruses cannot physically destroy your hard disk, although they can scramble the data on them.
• Viruses cannot destroy your computer’s RAM.
• Viruses cannot cause your computer system to explode.

People intentionally write computer viruses, they do not appear spontaneously. They are not accidental mutations of “normal” software. (more…)