Virus Descriptions

Overview The Internet has revolutionized the way most people use computers. E-mail, Web surfing, and the ability to quickly and easily download files and information has increased productivity and enhanced communication for both personal and business tasks. However, the same technology that allows these advances also allows the easy creation and distribution of harmful viruses and worms. Follow the links below to learn more about the most common computer viruses.

General Information Many of the most common viruses are spread via e-mail attachments. This page has general information about viruses and how you can protect your computer from virus infestation. This page has a list of some of the more common viruses currently roaming the Internet. Symantec Inc. has long been one of the leaders in virus detection and prevention. The company hosts this site that lists the latest virus threats, security advisories, and related information. You can also read descriptions of just about any virus ever written here. Another site that contains both descriptions and  infestation charts and charts is found at

Specific Viruses Follow the links below to read descriptions of some of the most common and destructive viruses.

  • The W32.Mydoom.M@mm worm is a mass-mailing worm that drops and executes a backdoor, detected as Backdoor.Zincite.A, that listens on TCP port 1034. The worm uses its own SMTP engine to send itself to email addresses it finds on the infected computer. Read about it here.
  • The klez worm is spread via e-mail and is one of the most difficult viruses to remove from a computer. Read about it here.
  • In 1999, the Melissa virus caused massive slowdowns, circling the world in less than 16 hours. This page has details.
  • The Code Red virus exploited a loophole in Windows servers. This page lists details.
  • W32.Netsky.P@mm is a mass-mailing worm that uses its own SMTP engine to send itself to the email addresses it finds when scanning the hard drives and mapped drives. You can read about this virus at this Web page.
  • Bugbear, a virus spread via mass mailing and open network shares, is smart enough to try to shut down virus protection applications. It not only affects computers, but can also flood printers and cause them to print large amounts of "garbage". Read about it here.

History  As early as 1991, IBM's Antivirus Research Center was studying and modeling the growth and spread of computer viruses. Read about the first paper to adapt the mathematical methods used in infectious disease studies to the new problem of computer viruses in the article "Directed-Graph Epidemiological Models of Computer Viruses," by Jeffrey O. Kephart and Steve R. White.  You can see a timeline of virus history here and an article about the history of viruses called "Brief History: A virus timeline" here.