A computer virus is one of thousands of programs that can invade computer systems (both IBM PC and Macintosh) and perform a variety of functions ranging from annoying (e.g., popping up messages as a joke) to dangerous (e.g., deleting files or destroying your hard disk). Trojan horses or worms are specific types of clandestine programs (loosely categorized as viruses) and can be just as dangerous. For simplicity’s sake, future mention of viruses in this document will refer to viruses, Trojan horses, and worms taken as a whole.
Computer viruses are programs that must be triggered or somehow executed before they can infect your computer system and spread to others. Examples include opening a document infected with a “macro virus,” booting with a diskette infected with a “boot sector” virus, or double-clicking on an infected program file. Viruses can then be spread by sharing infected files on a diskette, network drive, or other media, by exchanging infected files over the Internet via e-mail attachments, or by downloading questionable files from the Internet.
With dangerous viruses on the network, what can computer users do to protect their systems?
Here are just a few hints:
Be sure to install an anti-virus software program (see the next section) to guard against virus
attacks. Also, be sure you turn on the scanning features. It can’t protect you if it’s not enabled.
Practice caution when working with files from unknown or questionable sources.
Do not open e-mail attachments if you do not recognize the sender (though you may also receive viruses from people you know). Scan the attachments with anti-virus software before opening them.
Download files only from reputable Internet sites, and be wary when exchanging diskettes or
other media with friends.
Scan your hard drive for viruses monthly. Even with these precautions, new viruses may find ways to enter your computer system.
If your computer becomes infected with a virus, don’t panic! For most viruses, you can simply use your anti-virus program to scan and remove the virus. If your Definition Files are up-to-date, the program should be able to clean off all but the most recent viruses. In the case of rather nasty viruses, you may have some damaged files that cannot be fixed.
Even with active monitoring of computer systems, anti-virus software can only protect against viruses that it knows about. For this reason, update files (generally called Definition Files) for anti-virus software are needed every time there is a new virus release. On the Windows platform, this means an update roughly every week; the Macintosh has fewer new viruses to worry about so updates are usually done monthly. The software that ITS distributes has an “Auto Update” feature to automatically connect to a Web site and download the latest Definition Files.