What are computer VIRUSES?

In the early 1980's, if a programmer had said that a computer could be infected by "viruses," he probably would have been greeted with only sympathetic laughter from his colleagues. In the meantime the response to this problem has changed somewhat, due in part to extensive but not always factual publicity. But even today many users are under the false impression that computer viruses refer to viruses in the biological sense.

Of course this is not true. Computer viruses are programs, just like a spreadsheet or a word processor. This distorted picture of computer viruses is the reason that the spectrum of responses to this topic range from sympathetic laughter to a knowing grin up to a panic ova viral infection. Factual explanations about these matters have generally been ignored up to now. There have been reports of "promiscuous disks," of worms which eat through the computer, and "hard viruses which destroy the ROM." To bring a little clarity to this confusion, this book is intended to be a guide in the world of computer viruses.

First we should explain the origin of the term computer virus. We will use parallels between biological viruses and viruses in the computer.

Biological viruses                                                      

1. Attack specific body cells

2. Modify the genetic information of a cell other than originally intended |

3. New viruses grow in the infccted cell itself

4. An infected cell is not infected more than once by the same cell

5. An infected organism may not exhibit symptoms for a long time

6. Not all cells with which the virus comes in contact are infected

7. Viruses can mutate and thus cannot be clearly told apart

Computer viruses      

1. Attack specific programs (all *.COM, all *.EXE, etc.)

2. Manipulate the program: It performs tasks

3. The infected program produces virus programs

4. A program is infected only once by most viruses

5. The infected program can work without error for a long time

6. Programs can be made immune against certain viruses

7. Virus programs can modify themselves and possibly escape detection this way

(Try to compare between biological and computer virus one by one to get clear view and understanding)

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