Important Viruses types and recovery technique

There are many types of viruses, but the most important types of viruses are described below.

Boot sector virus 

We know that the disk is divided into tracks and sectors the disk on which the operating system has been loaded, has a special program in its first sector called the boot sector. When the computer is turned on, the program in the boot sector is automatically loaded into the memory.  This program then loads the operating system into the memory after performing some initial tasks. The boot sector virus modifies the program in the boot sector. It is loaded into memory whenever computer is turned on. This virus is attached with the executable files, i.e. .exe, .com, and .dll files. When these executable files are used by the user, the virus attached with these files is also activated. It infects other files and also performs destructive activities. It also destroys the data files.

Chernobal Virus 

The famous chernobal virus deletes all the Microsoft Office files and also the partition information from the disk. Once the partition of the disk is deleted, the important data on the disk cannot be accessed. 

Logic Bomb 

Logic bomb is a virus, which is activated on the basis of a logical condition. Examples of conditions that can be used as triggers for a logic bomb are the presence or absence of certain files, a particular day of the date etc. Once this virus is triggered, the important data stored into a computer may be deleted or corrupted.

Usually, this type of virus is created and installed by a programmer who is working in a organization on temporary basis. He installs the logic bomb in an accounting program to check for his name in the organization payroll system. If the employee is terminated, the logic bomb is triggered and the program may delete files of payroll system or may perform some destructive actions. 

Trojan Horse 

Usually, the Trojan Horse virus is the part of some computer game programs. When game program is installed in the computer and run, this virus is activated. An example of Trojan Horse is Format C.

Redlof 

Redlof virus is a polymorphic virus. It is written in visual basic script. Polymorphic means “changes nature with passage of time”. This virus changes its nature with passage of time and therefore, it is difficult to catch this virus by an anti virus program. Normally, this virus infects the file “Folder.htt”.  This file is the part of windows operating system. 

1. Some viruses may make invisible changes, hence corrupting the data being used and some virus may also make data unusable.
2. A virus program may detect some special information like passwords or any sensitive data and send it to some other user on a network. For example a virus program may read the “Pin code” of credit card, entered by a user and then send this information to another user.
3. A virus may make resources unavailable to the users. For example a virus after copying itself on all computers on a network, may affect the communication activity on the network, so that other users cannot use the network.