Computer Virus


VIRUS stands for -Vital Information Resources under Siege.

As defined A computer virus is a self-replicating program containing code that explicitly copies itself and that can ’infect‘ other programs by modifying them or their environment such that a call to an infected program implies a call to a possibly evolved copy of the virus.
It is a set of instructions that manipulate the functions of your computer's operating system. 'Virus' is actually a generic term for software that is harmful to your system. They spread via disks, or via a network, or via services such as email. Irrespective of how the virus travels, its purpose is to use or damage the resources of your computer.

The first viruses were spread as part of computer programs, or by hiding in floppy disks. Most modern viruses are spread by Internet services, in particular email. Malicious software or malware for short, are ―programs intentionally designed to perform some unauthorized -often harmful or undesirable act." Malware is a generic term and is used to describe many types of malicious software, such as viruses and worms.

Some viruses display symptoms, and some viruses’ damage files and computer systems, but neither symptoms nor damage is essential in the definition of a virus; a non-damaging virus is still a virus. There are computer viruses written for several operating systems including DOS, Windows, Macintosh, UNIX, and others. A typical structure of a computer virus contains three subroutines. The first subroutine, infect - executable, is responsible for finding available executable files and infecting them by copying its code into them. The subroutine do-damage, also known as the payload of the virus, is the code responsible for delivering the malicious part of the virus. The last subroutine, trigger-pulled checks if the desired conditions are met in order to deliver its payload.

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