Computer Virus

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 tthe
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 too 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 or file viruses infect executable files or pr

rograms 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 coombine 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 se
een 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.

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