What is a computer virus
Computer virus -Over the past few years computer have invaded almost all sphere of our life by increasingly playing a bigger and bigger role in various ways. The computer revoulation got a major shock when computer viruses intruded into the computer and started spoiling the system. The basic purpose of a computer viruses was to damage the program’s in the computer and spoil the operational mechanism. But do you know what is a computer virus?
A computer viruses is a program that in one way or other infects other programs by either modifying or destroying them it also spread or propagates or has the potential to do so. A computer viruses has a least the following four characteristics :
- It is a set of computer instruction.
- It is deliberately created.
- It propagates using host programs.
- It does undesirable things like causing damage or spoiling the operational mechanism.
From the above information it is implied that computer viruses are deliberately created software programs and should not be misunderstood as programming errors or hard ware malfunctions. The virus engaged itself in doing unwanted things like deleted files, formatting disk, changing the keyboard input etc.
There are different types of computer viruses with the different objectives but they can be broadly classified into two types:
Non- resident viruses
Resident viruses are those which on execution install their code in memory and infect other programs or discs from there on the other hand non residential viruses do not install themselves in memory but spread when an infected program is run.
There are four distinct phases of infection by a computer virus. They are :
- The dormant phase.
- The propagation phase
- The triggering phase
- The action phase
In the dormant phases the virus enters into the system but does nothing destructive to arouse the user,s suspicion. When one uses the infected program at this stage he finds nothing abnormal and carries on without any suspicion which gives the virus a chance to easily go on to the next phase of infection.
In the next phase that is propagation a viruses spread out as far as possible and infects other programs or disks.the virus also spread onto other system via diskettes, communication link etc. This is the most damaging phase as the virus spread from site to site system to system without any apparent efforts on their part rather it is the user who unknowingly helps in the propagation of the virus.
The third stage is the triggering stage when the virus get ready for the final act that is damaging.
One the triggering is pulled the virus moves onto the final stage of action which results in damage that we all know about .