Computer Viruses and Anti-Virus Software

Computer Viruses and Anti-virus Software

By

Mia L. Guidry

Table Of Contents

I Intro

II Computer Virus Components

a.Worms

b.Trojan horses

c.Logic bombs

III Types of Viruses

a.Boot sector virus

b.File virus

c.Macro virus

d.Multipartite virus

e.Polymorphic virus

f.Stealth virus

IV How Viruses Work

a.Virus introduced to system

b.Trojan activated

c.Logic bomb activated

d.Destructive part of virus activated

V Most Common Viruses

a.Jerusalem virus

b.Cascade virus

c.Brain virus

d.Italian virus

e.New Zealand virus

VI Macro Virus

a.What are they?

b.How do they work

VII How to Avoid Viruses

a.Removing floppies from drive

b.Don't use pirated software

c.Backup data

d.Run virus check program periodically

VIII Anti-virus Software

a.Why would you use?

b.Virus Scanner

c.Types of Anti-virus software

In this growing technological world, there is a dependency on computer systems. With the wide spread use of computer systems comes the threat of short programs that damage the system and other programs on that system. These short programs are called computer viruses. There are many computer viruses out there to infect unsuspecting system and programs. Along with these threats of infection comes the opportunity to eradicate these viruses before they infect systems. There are programs called anti-virus protection to help find and fix problems before they damage computer systems (Encyclopedia.com).

Computer Virus and Components

A computer virus can be defined as a rogue computer program, usually short in nature, designed to spread copies of itself to other computers and disrupt the computers' normal operation. These viruses usually attach or insert themselves in or to a program or boot sector of a disk. It is spread through floppy disk, network, or routine on-line services. There are some viruses that are harmless, but others can destroy or corrupt data and cause an operating system or application program to malfunction. The three most common types of destructive computer programs are the Trojan horse, logic bombs, and the worm. "A virus is considered to be a worm with a logic bomb or Trojan horse component" (PC Upgrade).

Worms are programs that copy themselves. They create images of themselves in a file or a certain part of a disk. The main reason for including a worm component in a virus is to spread the virus via floppy dick. Now every time

you format a disk or copy a disc, the worm now infects you floppy disk. The Trojan horse is a program hidden inside another useful looking program. When the useful program is running the Trojan horse is doing something like erasing your Fat and directory. The last of this triangle is the bomb. The bomb is a piece of code embedded in a program or the operating system that waits for a particular event to occur. When the event occurs the bomb goes off doing some kind of damage. These bombs show up as the most destructive part of the virus. For example, "If its Friday the 13th, erase the disk" (PC Upgrade).

Types of Viruses

Viruses can also be classified by their preferred habitat. There are viruses that attach themselves to other programs and they are called parasitic viruses. Some prefer lodging in the boot sector of your floppy or hard disk. These are called boot sector viruses. A boot sector virus affects the section of a floppy or hard disk that contains operating systems and file information. Meanwhile each time the personal computer is started it infects the floppy in the drove and spreads the virus. Next is the file virus, which infects programs with .EXE and .COM files. When the infected program has run, the virus copies itself. Multipartite virus uses a combination of techniques to spread itself every time

it spreads. Since the polymorhic viruses' signature changes randomly the common signature scanning methods often fail to find them. A macro virus is the most common type that currently accounts for about 80 percent of computer infection. For example, Microsoft word and Excel macros execute a series of instructions automatically each time you open a document. If and automatic macro has been infected by a virus, it can damage any word or excel document that is opened (PC World). Some viruses are said to be "stealth". This virus attempts to hide itself by keeping a copy of the parts of the dick that has been affected before it was affected. In other words, the virus uses tricks to conceal itself from anti-virus software. The stealth virus affects DOS for the most part.

How Do Viruses Work

Viruses will be introduced to your system either with an infected. Com or .exe file or the boot from the floppy with an infected

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