Computer Viruses
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

Three types of viruses are boot sector virus, 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 computers memory. Once a virus is in a 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 a 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 disc space remains.

To detect computer viruses, antivirus programs have been developed. Besides detecting viruses,
antivirus programs also have utilities to remove or repair infected programs and 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.

Techniques for Virus Protection and System Backup
Using Virus Protection SoftwareBacking 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 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).

Works Cited
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. (6 Nov. 1998).

Reed, Margaret E. An Introduction to Using Computers. Chicago: West Davidson Jones
Publishing Company, 1998.