What is a virus?
A VIRUS is a small, executable program with the ability to replicate itself by adding its code to that of a host program or the system area of a hard disk. The user is generally unaware of the actions of a virus as it replicates and usually only becomes aware of its presence when the virus 'activates', which it does according to a given set of conditions.Once the user knows what signs to look for, it can be very obvious when viral activity occurs... Let's discuss the difference between viruses.....
Every virus has its own personality. Viruses differ in many ways, each having its own unique properties that make it different. Here are some ways that viruses differ from each other:
- SIZE - A virus can be as small as 66 bytes or less, or as large as 4096 bytes or more. Compared to most computer programs a virus must be very small.
- METHOD OF INFECTION - A virus can infect the host program in different ways. Below are three methods commonly used. They are by no means the only ways, but they are the most common. It is possible for a virus to use one or more of these methods.
- OVERWRITING - When a virus infects using this method, it will simply write a copy of itself over the begining of the host program. This is a very simple method and is used by more primitive viruses. Overwriting tends to make the user suspicious because the host program no longer functions. This method of infection causes no change in the size of an infected program.
- APPENDING - This method is a bit more complex. The virus appends itself onto the end of the host program and also edits the begining of the program. When the user runs the infected program ....
