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 
85-102).
	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.
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 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. 
	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.