Nothing To Sneeze At

It began with an electronic Christmas card that mysteriously materialized last December on terminals connected to one of IBM's research computer networks. Soon after came news that some desktop computers at Hebrew University in Israel were growing more and more lethargic, as if a hidden organism were sapping their strength. Then, one day last month, thousands of Macintosh users were greeted with an unexpected "message of peace" from the publisher of a Canadian computer magazine, which flashed briefly on their screens and disappeared without a trace.

The computer world has been struck by an epidemic of "viruses," tiny fragments of computer software created by mischievous programmers and hidden within the instructions of a larger program. Like their biological namesakes, computer viruses are characterized by an ability to replicate and invade other software with which they come in contact. Thus they can be spread from computer to computer by unsuspecting users who either swap disks or send programs to one another over telephone lines.

So far, most of the viruses that have come to light this year have been relatively benign, like the strain currently making the rounds of the public computer networks that causes infected machines equipped with voice synthesizers to intone the words "Don't panic." But the epidemic is giving the computer industry a chill. The virus that struck Macintosh owners last month was apparently spread through a program called FreeHand which is published by Seattle-based Aldus Corp. FreeHand is the first commercial software product known to have been a virus carrier. The bug could just as easily have instructed its host computers to erase their storage disks. Several companies are now marketing "vaccine" programs that offer some protection against uninvited invaders, but none are foolproof. Experts advise users to make backup copies of their important disks and to regard each new piece of software as a potential carrier until it has been thoroughly tested.