When things go wrong

Virus

Viruses and errors are common in the ICT world. They are essential to understand and know how to deal with them. A properly engineered virus can have an amazing effect on the Internet or on a network of some type.

Computer viruses are called viruses because they share some of the traits of biological viruses. A computer virus passes from computer to computer like a biological virus passes from person to person. A computer virus must piggyback on top of some other program or document in order to get executed. Once it is running, it is then able to infect other programs or documents.

Early viruses were pieces of code attached to a common program like a popular game or a popular word processor. A person might download an infected game from a bulletin board and run it. A virus like this is a small piece of code embedded in a larger, legitimate program. Any virus is designed so it runs first when the legitimate program gets executed. The virus loads itself into memory and looks around to see if it can find any other programs on the disk. If it can find one, it modifies it to add the virus's code to the unsuspecting program. Then the virus launches the "real program." The user really has no way to know that the virus ever ran. Unfortunately, Two programs are infected, when the virus reproduced itself. The next time either of those programs gets executed, they infect other programs, and the cycle continues.

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If a floppy disk, with a virus-infected program is loaded onto another computer, the virus starts spreading very fast. Also any program that the contents is not known and is being downloaded could be a virus. Viruses travel fast using both these ways. The spreading part is the "infection" phase of the virus. Viruses wouldn't be so bad if all they did was replicate themselves, but they don’t.  Unfortunately, most viruses also have some sort of destructive "attack" phase where they do some damage. Some sort of trigger will activate the attack phase, and the virus will then "do ...

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