what is a computer virus?

Answer 1

A program or piece of code written by a cracker that "infects" one or more other programs by embedding a copy of itself in them, so that they become Trojan horses. When these programs are executed, the embedded virus is executed too, thus propagating the "infection". This normally happens invisibly to the user.

A virus has an "engine" - code that enables it to propagate and optionally a "payload" - what it does apart from propagating. It needs a "host" - the particular hardware and software environment on which it can run and a "trigger" - the event that starts it running.

Unlike a worm, a virus cannot infect other computers without assistance. It is propagated by vectors such as humans trading programs with their friends. The virus may do nothing but propagate itself and then allow the program to run normally. Usually, however, after propagating silently for a while, it starts doing things like writing "cute" messages on the terminal or playing strange tricks with the display (some viruses include display hacks). Viruses written by particularly antisocial crackers may do irreversible damage, like deleting files.

By the 1990s, viruses had become a serious problem, especially among IBM PC and Macintosh users (the lack of security on these machines enables viruses to spread easily, even infecting the operating system). The production of special antivirus software has become an industry, and a number of exaggerated media reports have caused outbreaks of near hysteria among users. Many lusers tend to blame *everything* that doesn't work as they had expected on virus attacks. Accordingly, this sense of "virus" has passed into popular usage where it is often incorrectly used for a worm or Trojan horse.

Answer 2

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Answer 3

Computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation.

A virus might corrupt or delete data on your computer, use your e-mail program to spread itself to other computers, or even erase everything on your hard disk.

Viruses are most easily spread by attachments in e-mail messages or instant messaging messages. That is why it is essential that you never open e-mail attachments unless you know who it's from and you are expecting it.

Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files.

Viruses also spread through downloads on the Internet. They can be hidden in illicit software or other files or programs you might download.

To help avoid viruses, it's essential that you keep your computer current with the latest updates and antivirus tools, stay informed about recent threats, and that you follow a few basic rules when you surf the Internet, download files, and open attachments.

Once a virus is on your computer, its type or the method it used to get there is not as important as removing it and preventing further infection.

Answer 4

It's dangerous and hostile malicious code that attacks a Computers operating system a virus can replicate itself or can be activated under certain conditions to launch a deadly payload. A virus can be be a Trojan horse a backdoor program that lets a remote attacker completely control a computer and follow his instructions like launch denial of service attack.

Answer 5

Viruses are nasty things, do regular scans with antivirus to make sure you are not infected here's a list of free ones http://www.basicspywaretips.com/freevirusremovaltool.html

Answer 6

You can get some info here: http://www.mbusbyuk.info/security.html