A tiny rogue program could easily disable your computer and erase all your files--programs and data. Raymond W. Elliott, CPA, a partner in the national auditing directorate of Coopers & Lybrand, describes the danger of such programs and how to protect against them. He is chairman of the Information Technology Research Subcommittee of the American Institute of CPAs. Like their biological namesakes, computer viruses can cause either inconvenience or worse, death-loss of important electronic data. Although some viruses are just sophomoric localized pranks, many of them get out of hand, triggering an epidemic fatal to thousands of computers.
A virus is a small, stealthy program designed to perform some computer act or function, either immediately or at some future time. Any number of events can trigger the embedded virus to activate: the occurrence of Friday the 13th or performing such a simple computer function as evoking a directory. In some cases, viruses simply display a harmless message on the screen; other times they destroy all the stored programs and data files; in extreme cases, they even can destroy computer components.
What makes viruses especially dangerous is that they're highly contagious. Once one gets a foothold in a computer, it almost surely will infect many other computers-with just a brief contact.
Viruses are spread in these ways: by transfering executable files from off a floppy disk, from off a network or by downloading an executable file through a modem.
No computer is immune. There is no practical, infallible way to guard against all possible viruses except through total "abstention"-isolating a computer so it does not use any software or files but its own. For obvious reasons, that's not a practical solution for most CPAS.
And once infected, there is no guarantee of an easy cure without "sterilizing" the computer's entire storage and memory, which means reformatting, or cleansing the hard disk, which results in the loss of all stored data and program files.
However, fairly effective protection and cure techniques are available. Unfortunately, the more effective they are, the more demanding are the mandated safety rules and needed compliance.
ANATOMY OF A VIRUS
Until a few years ago, software pranks were unheard of-except in university computer-lab circles. Mischievous students would sneak a virus into a friend's computer so that at a predetermined moment a message would pop up on the screen-such as "Got ya! " or "Happy Birthday, nerd! "
In a typical infection, a virus is hidden in what's called an executable file, which is a file that contains the instructions of a working program. Usually these files are labeled with a .EXE or COM extension, as in KEYBDRVR.EXE or COMMAND.COM.
When the file is introduced to the computer-via a floppy disk, a download from a bulletin board, or through a network-the program causes itself to be implanted onto the computer, usually onto the hard disk. The virus then copies itself onto other stored programs each time one of those programs is evoked. As a result, the duplication process accelerates at exponential speeds. In some cases, the fertile little programs multiply so prolifically that they soon saturate the computer, grinding it to a halt.
In network arrangements, where computers are linked, program sharing is allowed and proper operational and security measures are not consistently practiced, the speed of contagion is fastest.
If a floppy disk is introduced into an infected computer, it does not necessarily have to contain an executable file for it to become infected or function as a carrier. A certain type of virus, known as a boot sector virus, will infect computers when they are first booted up (turned on) with an infected disk in a drive.
In recent years, the stealth and destructiveness of viruses has accelerated. An increasing number have infected the business world; at least one has paralyzed a military computer network. …