A computer virus is an illegal and potentially damaging computer program
designed to infect other software by attaching itself to any software it
contacts. In many cases, virus programs are designed to damage computer systems
maliciously by destroying or corrupting data. If the infected software is
transferred to or accessed by another computer system, the virus spreads to the
other system. Viruses have become a serious problem in recent years, and
currently, thousands of known virus programs exist (Reed 85-102). Three types of
viruses are a boot sector viruses, file virus, and Trojan horse virus. A boot
sector virus infects the boot program used to start the system. When the
infected boot program executes, the virus is loaded into the computer’s
memory. Once a virus is in memory, it can spread to any floppy disk inserted
into the computer. A file virus inserts virus code into program files. The virus
then spreads to any program that accesses the infected file. A Trojan horse
virus (named after the Greek myth) hides within or is designed to look like a
legitimate program. Some viruses interrupt processing by freezing a computer
system temporarily and then displaying sounds or messages. Other viruses contain
time bombs or logic bombs. A time bomb is a program that performs an activity on
a particular date. A logic bomb is a program that performs an activity when a
certain action occurs, such as an employee being terminated. A worm, which is
similar to a virus, copies itself repeatedly until no memory or disk space
remains. To detect computer viruses, antivirus programs have been developed.
Besides the detecting of the viruses, antivirus programs also have utilities to
remove or repair infected programs or files. Some damaged files cannot be
repaired and must be replaced with uninfected backup files. The table below
outlines some techniques used to protect computer systems. Table Techniques for
Virus Protection and System Backup Using Virus Protection Software Backing Up
Your System Install virus protection software on every computer system. Develop
a regular plan for copying and storing important data and program files. Before
use, scan every floppy disk with a virus scan program to check for viruses.
Implement a backup plan and adhere to its guidelines. Check all programs
downloaded from the Internet or bulletin boards for viruses. Keep backup copies
of files in fireproof safes or vaults or off-site If your system becomes virus
infected and you have questions, contact the National Computer Security
Association (NCSA) for low-cost assistance (Elmhurst, 6 Nov. 1998). 
Bibliography
Chambers, Anita R., and Zachary W. Peters. “Protecting Against Virus
Attacks.” Computers May 1998: 45-62. Elmhurst, Mark. “Virus Infection: Where
to Obtain Assistance” Word 97, Project 3. http://www.scsite.com/wd97/pr3.htm
(6 Nov. 1998). Reed, Margaret E. An Introduction to Using Computers. Chicago:
West Davidson Jones Publishing Company , 1998.