Computer viruses are small software programs that are designed to spread from one computer to another. Computer viruses comes in different forms in these days. We are going to describe two types of categories such as : what they infect and how they infect.How virus works:
- An infected file is run. This is either a program file, or a boot sector program at the boot time.
- The infected program has been modified so that instead of the proper code running, the virus code runs instead.
- The virus code becomes active and takes control of the PC.
- What exactly the virus does depends on what the virus is written to do. Their primary goals however include replication and spreading.
Most common types of Viruses:
- Resident Virus
This type of virus is permanent and which resides in the RAM memory. Corrupting files and programs that are opened, closed, copied and renamed. Eg: Meve, CMJ, Randex
These viruses are distributed throughout the infected media and usually hides in the memory.
Direct Action Viruses
The main purpose of this virus is to replicate and take action when it is executed.
Virus of this kind is characterized by the fact that, it deletes the information contained in the files that infects. Eg: Trj.Reboot
- Network virus
Network virus rapidly spread through a Local network area, and sometimes through the internet. Eg: Nimda, SQLSlammer are most dangerous network viruses.