How Computer Viruses Work

How to Protect Your Computer from Viruses

You can protect yourself against viruses with a few simple steps:

If you're truly worried about traditional (as opposed to e-mail) viruses, you should be running a more secure operating system like Linux and, to a lesser extent, Apple's Mac OS X. You never hear about viruses on these operating systems because they represent such a small part of the market they're targeted by far fewer viruses than the Windows operating system. Apple's OS X has seen its share, but viruses are still predominately a Windows problem.

If you're using an unsecured operating system, then installing virus protection software is a nice safeguard. Many anti-virus options are available for free online.

If you simply avoid programs from unknown sources (like the Internet), and instead stick with commercial software purchased on CDs, you eliminate almost all of the risk from traditional viruses.

You should make sure that Macro Virus Protection is enabled in all Microsoft applications, and you should NEVER run macros in a document unless you know what they do. There is seldom a good reason to add macros to a document, so avoiding all macros is a great policy.

You should never double-click on an e-mail attachment that contains an executable. Attachments that come in as Word files (.DOC), spreadsheets (.XLS), images (.GIF), etc., are data files and they can do no damage (noting the macro virus problem in Word and Excel documents mentioned above). However, some viruses can now come in through .JPG graphic file attachments. A file with an extension like EXE, COM or VBS is an executable, and an executable can do any sort of damage it wants. Once you run it, you have given it permission to do anything on your machine. The only defense: Never run executables that arrive via e-mail.

By following these simple steps, you can remain virus-free.

For more information on computer viruses and related topics, see the links below.

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More Great Links


  • "Avoiding Social Engineering and Phishing Attacks" U.S. Computer Emergency Readiness Team. (Oct. 4, 2007)
  • Baratz, Adam, and McLaughlin, Charles. " Malware: what it is and how to prevent it" Ars Technica. Nov. 11, 2004. (Oct. 8, 2007)
  • Boutin, Paul. "Slammed! An inside view of the worm that crashed the Internet in 15 minutes." Wired Magazine. July 2003 (Oct. 3, 2007)
  • Johnston, Stuart J. "Bugs & Fixes: Save Your PC From Virus Attacks." PC World. 2/27/2002. (Oct. 8, 2007),81968/article.html
  • Kaplan, Dan. "Storm Worm making comeback with new spam run." April 28, 2010. (Oct. 29, 2011)
  • Kawamoto, Dawn. "Storm worm rages across the globe." CNET January 19, 2007 (Oct. 4, 2007)
  • Leedham, Robert. "Android Gingerbread virus poses fresh smartphone threat." Aug. 22, 2011. (Oct. 30, 2011)
  • Lemos, Robert. "Worm double whammy still hitting hard." CNET Aug 21, 2003 (Oct. 5, 2007)
  • McAfee fact sheet on ILOVEYOU virus. (Oct. 3, 2007)
  • "Worst virus in years infects 6.5 million computers." Jan. 16, 2009. (Oct. 30, 2011)
  • "Mydoom virus floods computers worldwide." Times Online. Jan. 27, 2004 (Oct. 3, 2007),,1-979473,00.html
  • Permeh, Ryan and Maiffret, Marc. "ANALYSIS: .ida "Code Red" Worm." eEye Digital Security. July 17, 2001 (Oct. 3, 2007)
  • Rhodes, Keith A., Chief Technologist, U.S. Government Accounting Office. "Information Security: Code Red, Code Red II, and SirCam Attacks Highlight Need for Proactive Measures" Aug. 29, 2001 (Oct. 5, 2007)
  • Schneier, Bruce. "Gathering 'Storm' Superworm Poses Grave Threat to PC Nets." Oct. 4, 2007. (Oct. 4, 2007)
  • Turner, Dean, Executive Editor, et. al.; "Symantec Internet Security Threat Report: Trends for January-June 07" Sept. 2007. (Oct. 8, 2007)
  • US-CERT advisory on the Melissa virus. Mar. 27, 1999. (Oct. 3, 2007)
  • "Virus Top Twenty for September 2007" Kaspersky Lab. Oct. 1, 2007. (Oct. 8, 2007)