how to understand about virus in computer

Virus of computer

Fighting computer viruses is a familiar task for every network administrator and most home users today. Several reports have shown that more than 90% of business users encounter viruses in their work. The damages caused by viruses are also significant.

The term virus covers a wide range of computer programs that have one thing in common. Once released, they replicate in a way that cannot be controlled by their author. This can easily, intentionally or unintentionally, lead to worldwide epidemics where millions of computers may become infected. Significant damage may result even if the virus author did not include malicious code in the virus. The virus problem has increased in importance over the past ten years. The first viruses were merely an annoyance that did not cause much harm for any business. Our

way to conduct business has, however, become more and more dependent on

computers and the Internet. New viruses that benefit from modern networking

technology have also emerged. This leads to a situation where new viruses spread

faster and faster. Much more critical systems may also be hit by viruses today.

This trend can clearly be verified by examining reports about economical damage

caused by computer-related crime.

The purpose of this paper is to shed some light on the way viruses work, what they

require from the environment to succeed and how the virus situation has evolved

over the past ten years. The ultimate benefit for the reader is better understanding

of the problem, which makes it easier to assess the threat from computer viruses,

to plan computer systems and to handle virus outbreaks. However, this paper does

not cover virus prevention and scanning techniques.

Viruses may occur on almost any computer platform with enough programming

capability. All kinds of personal computers such as PCs, Mackintoshes etc. belong

to this category. Handheld computers, such as Palm, Pis-ion and Pocket PC, are

actually also suitable environments for viruses. The virus problem, however, is

worst in the PC environment. Both the number of known viruses and the

likelihood of being infected is by far the highest in this environment. For that

reason, only PC viruses will be covered in this paper.

A virus is by definition a computer program that spreads or replicates by copying

itself. There are many known techniques that can be used by a virus, and viruses

appear on many platforms. However, the ability to replicate itself is the common

criterion that distinguishes a virus from other kinds of software.

The term virus is quite often misused. Some viruses contain routines that damage

the computer system on which it runs. This so called payload routine may also

display graphics, play sounds or music etc. This has lead to a situation where

viruses are assumed to cause deliberate damage, even if there are many viruses

that don’t. The term virus has, for these reasons, become a synonym for malicious

software, which is incorrect from a technical point of view.

The process of spreading a virus includes both technical features in the virus itself

and the behavior of the computer user. Most viruses are by nature parasitic.