Internet virology 101

CMAJ 1998;158:1522

© 1998 Canadian Medical Association

• Computer viruses: immunize yourself!

The most effective defence against a computer virus is knowledge. Knowing what viruses are, how they are transmitted and how to "inoculate" yourself against infection can dramatically reduce the threat they pose. Let's go to war!

A virus is a set of computer instructions that, when executed, spreads to other programs or files. Often it will lurk in a computer's memory, waiting to infect any file, program or disk that is accessed. Depending on its creator's motives, a virus can do anything from causing your computer to display a harmless message to altering the contents of a file to erasing files and programs permanently. Even if the virus does nothing detectable, it can cause peripheral damage by consuming scarce computer resources such as disk space or processor time as it replicates itself.

As with tumours, there are 2 classes of viruses: benign and malignant. Fortunately, most of them are benign and aren't designed to do any real damage. Usually they simply display a message on the infected machine.

A malignant virus, on the other hand, is truly evil because it will attempt to inflict malicious damage, such as modifying or deleting information stored on a computer's hard drive.

Viruses are transmitted when an infected application is launched or if a computer is started-up using an infected diskette. Here are the most common methods of entry:

• software introduced into or used on a system by an unauthorized user who has access to it;
• software imported by an employee whose home computer is infected;
• software purchased from a software vendor whose facilities are infected;
• software downloaded from the Internet or a bulletin-board service; and
• software intentionally infected by a malicious or disgruntled employee, with software referring to any program, operating system or file.

When I worked as network security manager for a federal government department, all virus infections over a 3-year period were traced to industrious employees who had taken work home and subsequently introduced viruses to the workplace via home computers that were infected.

Recently, there has been a rash of warnings circulating over the Internet that describe the great catastrophe that will befall the poor, hapless soul who dares to open an email containing a particular subject line.

Ignore them, because the messages are hoaxes: you cannot contract a computer virus simply by reading an email text message. However, there is a significant threat that any attachment to an email message may contain a virus that can be transmitted when the attachment is executed. During the holidays, I was horrified to see that many users were gleefully forwarding email attachments that consisted of animated season's greetings.

These animations are, in fact, executable programs, and any one of them could have been a virus. As these messages were circulated widely, the results could have been catastrophic.

Looking for more information? Good sources of general information are found at www.symantec.com/avcenter/vinfodb.html or www.antivirus.com/vinfo/vprimer.htm.

For information about Internet email hoaxes, contact ciac.llnl.gov/ciac/CIACHoaxes.html (this address is case sensitive). — Warren Lampitt, warren@gretmar.com, is director of information systems at Gretmar Communications, an Internet/intranet development firm located in Timmins, Ont. He provides lectures and hands-on tutorials for physicians who wish to use the Internet effectively.

Three webbed feet up for CMA Online

Dr. Barrie McCombs, the director of the Medical Information Service at the University of Calgary who is perhaps better known as the Web-footed Physician in the Alberta Doctors' Digest, has given the CMA's Web site, CMA Online, his top rating — 3 webbed feet. This is awarded to "excellent sites" that should be "visited regularly." Sites that received 1 webbed foot are only considered fair and should be visited rarely, while sites with 2 feet are worth an occasional visit.

McCombs, a family physician (bmccombs@acs.ucalgary.ca), said in his review in the Digest's March/April issue that many sites could be improved by considering what visitors want to know rather than what organizations want to say.

McCombs said he saves his highest rating for sites that have a well-organized, informative main page or that provide information that is useful to physicians who are not members of the organization.—Patrick Sullivan

Send a letter to the editor Envoyez une lettre à la rédaction