There are large numbers of computer virus and malicious code present that can infect the network. A virus can enter the computer if it interacts with other computers or programs or data from an infected computer. Whenever a computer is infected with a virus, it becomes extremely slow, generates strange error messages or even locks up the computer or affects the functioning of the computer. A virus is a program that has two functions: one is proliferate and other is activate. Proliferate means is to make more copies of itself and activate means to activate the virus at particular time and date to causing the damage. There are five typical types of viruses, they are:
a. Boot sector
Antivirus programs protect your system in two ways. It acts in active seek and destroy mode as well as in a passive sentry mode. In the active seek and destroy mode the active program scans the computers boot sector and files for viruses. If it finds any viruses it asks the user if to quarantine or remove the infected files. In the passive sentry mode the antivirus programs passively monitors the computer activity and checks for viruses when an event such as file is being downloaded or program is being executed. Antivirus programs use different techniques for fighting against viruses. It detects the boot sector viruses by comparing the drives boot sector to a standard boot sector. The technique works because most of the computer boot sectors are the same. Some antivirus programs also keep the copy of the boot sector and replace the infected boot sector by the copy if it detects a virus. To detect the executable viruses, the antivirus program uses a signature library. The signature is a code pattern of a known virus. The antivirus programs than compares the executable file with the signature library which is library of code pattern of known viruses. Antivirus programs detect macro viruses using virus signature or certain macro commands that indicate known macro virus.
Tips to Prevent Virus Infection
1. Loss due to virus attacks can be prevented by not allowing the virus from entering the system.
2. It is better to use the antivirus shield that automatically scans copies and downloaded files.
3. It is also necessary to scan the system daily for virus attacks.
4. It is also necessary to check all the removable media that was exposed to the system and any other machine that may be affected by a virus attack.
5. It is a best practice to disable all removable media in a corporate network by implementing group policies to prevent the virus from entering the system via removable media.
6. The antivirus program installed in the computer should be updated regularly with the latest definitions.
7. Prevent unknown users from accessing your workstations.
8. Secure your workstations by assigning complex passwords.
9. It is a best practice to prevent standard users from installing any software’s on your workstation computers by settings appropriate permissions.
10. Always ensure that your system contains genuine copy of operating system and other software’s as system using pirated copies are more prone to be infected with virus.