Precautions can keep viruses out

Computer Life column for 4/19/97 by
Richard Gordon

Amidst the oohing and aahing over presents and children at a recent birthday party for a 1-year-old friend of mine, a couple of computer conversations broke out.

One was a trans-generational discussion of Web search tools between a gray-haired grandfather, a teenage boy and a thirty-something woman.

Later, out by the beer cooler, a more serious conversation began. One guest held our attention as he told us about spending 15 or 18 hours that week eradicating a virus from his network. He pointed a carrot stick right at me and added, "That's something you should tell your readers."

The kinds of viruses

Some viruses erase or damage files as they spread, others are mere nuisances. But there are three basic types: boot sector, program, and macro viruses.

Boot sector viruses reside in a part of a disk or diskette that is ordinarily hidden from your view, in the part that helps your computer locate and read the information on that disk.

This type of virus appears on a computer's hard disk after you place an infected diskette into a Macintosh system's disk drive or after you try to boot a Windows or DOS computer with an infected diskette in the "A" drive.

Once your computer's hard disk is infected, any diskette you use can become infected.

A program virus attaches itself to a runnable computer program. It only copies itself when you run an infected program, attaching itself to other programs you run. If you are using, say, Microsoft Word, a program virus could attach itself to the Word program itself and spread to Excel or Paintbrush. But this type of virus does not attach itself to the documents you have prepared.

This is what makes the third type of virus particularly tricky: macro viruses spread using individual documents as hosts, attaching themselves to basic template or start-up files used to create new documents.

Many of these macro viruses spread quickly if you set your desktop e-mail reader to open any attachments automatically. If you receive an infected file attached to an e-mail message and if your mail program automatically fires up another program to open that file, your files can be infected.

My carrot-wielding friend's work group were using e-mail to review a document prepared with Microsoft Word. A copy became infected, and before long, the entire workgroup had inadvertently infected their systems.

Safe computing

Don't panic. If you take proper precautions, you can make sure you do not lose any information to a virus.

  1. Make copies of important files and keep them on diskettes or tapes away from your computer. That way, should a disaster strike (including a virus attack), you can recover your information.

  2. Use virus protection software.

    • Scan every diskette that someone gives you. If they object, tell them it's for their protection: if their diskette is infected, their system is at risk, too.

    • Scan every program you download.

    • Periodically scan your entire hard drive.

    • Do not set your mail program to automatically launch another program to view files sent to you as e-mail attachments. Scan and disinfect the files before you open them.

Which virus protection?

A lot of good software is available for Mac and Windows users. Norton's Symantec is solid software for both platforms ( McAfee Associates VirusScan software is also available for both platforms ( Command Software distributes F-Prot and a related macro-virus-scrubber for DOS and Windows systems, available in both a "shareware" and "professional" version (

c|net has a list of other software that will do the trick on both platforms (

OK, if your computer is really safe, you may return to the party.

Copyright © 1997, The News Journal Company

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Richard Gordon helps support faculty, staff and student computing at the University of Delaware. E-mail questions, comments or suggestions to, or write him at The News Journal, Box 15505, Wilmington, DE 19850. Although each note cannot be answered individually, reader comments and questions will often be incorporated in future columns.