COMPUTER VIRUSES

Introduction:

Virus in reference to computers was first used by David Gerrold   in his book “When Harline was one” in 1972.He named a computer program as virus which rang telephone numbers randomly until it found another

Computer linked to the network.

      A Virus  reproduces  , usually without your permission or knowledge. In general terms they have an infection  phase  where they reproduce widely and

an attack phase where they do whatever damage they are programmed to do.

There are large number of virus types.

       Computer viruses , like biological  counter parts generally trick hosts are other computers into reproducing copies of the   invading organism . They spread from computer to computer through electronic bulletin boards telecommunication systems,

And shared Floppy disks.Viruses are created by human programmers , for  fun   or malice,but once they began to spread they take on a life of their own, creating description

Dismay and paranoia in their wake.

      The operating system provide protection against virus. Some  software vendors do provide protection from virus, but it is the user who should ultimately deal with it.The user should detect and stops the virus from spreading. If Virus is found in any of the PC’s

That PC should immediately be isolated. The virus is removed by giving an antidote of studying virus. The machine should  be put into use only after the virus is eliminated.

Virus Definition:

    A Virus is a program that reproduces its  own code by attaching itself to other  executable files in such a way that the virus code is  executed when the infected  executable file is executed.

      A virus is a piece of programming code usually disguised as something else that causes some unexpected and, for the victim, usually undesirable event and which is Often

designed so that it is automatically spread to other computer users.   Viruses can be transmitted by sending them as attachments to an e-mail note, by  down loading  infected programming from other sites, or be present on a diskette or CD.  The source of the e-mail note, downloaded file, or diskette you have received is often unaware of the virus.   Some viruses wreak their effect as soon as their code is executed; other viruses lie dormant until circumstances cause their code to be executed by the computer.  Some viruses are playful in intent and effect ( Happy  Birthday, Ludwig! ) and some can be quite harmful,erasing data or Causing your hard disk to require refo0rmatting.

           To attach might mean physically adding to the end of a file, inserting into the middle of a file, or simply placing  a pointer to a different location on the disk somewhere where the virus van find it.

          Most viruses do their job by placing self-replicating code in other programs so that when those other programs are executed, even more programs are infected with the self-replicating code, when triggered by some event, may do a potentially harmful act to your computer.

       Another way of looking at viruses is to consider them to be programs written to create copies of themselves.These programs attach these copies onto host programs .

When one of these hosts is executed , the virus code executes, and links copies of itself to even more hosts.

        Similar to viruses, you can also find malicious code in Trojan Horses, Worms, and logic bombs.Often the characteristics of both a virus and a warm can be found in the same beast, confusing the issue even further.