Today I’m going to talk about: Computer virus

I’ve divided my presentation into two parts:

First I’d like to introduce of this virus and second I’ll present

types of virus.

So, let’s start with introduce

Virus (computer), self-duplicating computer program that interferes

with a computer’s hardware or operating system. Viruses are designed to

duplicate or replicate themselves and to avoid detection. Like any other

computer program, a virus must be executed for it to function, it must be

located in the computer’s memory, and the computer must then follow the

virus’s instructions. These instructions are called the payload of the

virus. The payload may disrupt or change data files, display an irrelevant

or unwanted message, or cause the operating system to malfunction.Computer

viruses activate when the run programs are opened. Once a virus is active,

it may replicate by various means and tries to infect the computer’s files

or the operating system. For example, it may copy parts of itself to floppy

disks, to the computer’s hard drive, into legitimate computer programs, or

it may attach itself to e-mail messages and spread across computer networks

by infecting other shared drives.

Finally let’s consider: with types of viruses

There are five categories of viruses: parasitic or file viruses,

bootstrap sector, multi-partite, macro, and script viruses.

Parasitic oor file viruses infect executable files or programs in the

computer. These files are often identified by the extension . File viruses

leave the contents of the host program unchanged but attach to the host in

such a way that the virus code is run first. These viruses can be either

direct-action or resident. A direct-action virus selects one or more

programs to infect each time it is executed. A resident virus hides in the

computer’s memory and infects a particular program when that program is

executed.

Bootstrap-sector viruses reside on the first portion of the hard disk

or floppy disk, known as the boot sector. These viruses replace either the

programs that store information about the disk’s contents or the programs

that start the computer. Typically, these viruses spread by means of the

physical exchange of floppy disks.

Multi-partite viruses combine the abilities of the parasitic and the

bootstrap-sector viruses, and so are able to infect either files or boot

sectors. These types of viruses can spread if a computer user boots from an

infected diskette or accesses infected files.

Other viruses infect programs that contain powerful macro languages.

These viruses, called macro viruses, are written in macro languages and

automatically execute when the legitimate program is opened.

Script viruses are written in script programming languages, such as

VBScript (Visual Basic Script) and JavaScript. These script languages can

be seen as a special kind of macro language and are even more powerful

because most are closely related to the operating system environment. The

„ILOVEYOU“ virus, which appeared in 2000 and infected an estimated 1 in 5

personal computers, is a famous example of a script virus.