Computer Virus

What is the definition of computer virus exactly? Well, a computer virus is a program, a block of executable codes, which attach itself to, overwrite or otherwise replace another program in order to reproduce itself without a knowledge of a PC user.

There are many different types of computer virus: Boot sector virus, file virus, direct action virus, Multi partition virus, Polymorphic virus, Stealth virus, and Macro virus.

1. Boot sector Virus

This type of virus is a common virus; duplicate itself by oppressing the boot sector. So that when the computer is booting, the virus will be automatically executed in the computer’s memory.

2. File Virus

Attacking files which are executed by an operating system. Usually this kind of virus attack file that have .com or .exe extension.

3. Direct action Virus

This kind of virus will enter the computer’s memory to execute other files, and then execute the other program in order to deceive the user.

4. Multi partition Virus

This type of virus is the combination between boot sector virus and file virus.

5. Polymorphic Virus

A kind of virus which is designed to deceive AV program, by changing its structure, after executing some command.

6. Stealth Virus

Controlling DOS level instructions by controlling the interrupt table.

7. Macro Virus

Written in a programming language from an application, so that virus has platform independent characteristic.

The difference between Computer Virus and other Computer program

1. The ability to get some important information from the user’s computer.

Virus is designed to infect many files or programs. For example, virus will infect all .txt or . htt files, so that virus will look for information about the existing files or program. After they done it, those important information will be hidden in other directories in order to deceive the user.

2. The ability to check program or file

When a virus is infecting a file, virus should be able to check whether a file has infected or not.

3. The ability duplicating itself

This is the first ability which has to be had by a computer virus.

4. Ability to manipulate

This ability is used to show messages, picture, deleting files, stealing files or data, etc.

5. The ability to hide itself

All of the virus’s activity must be invisible either for the user and for computer.

The structure of Virus:

1. The virus identity code

Every single virus has a unique identity that no other virus has. For example, virus A has X identity, and virus B has Y identity, so those virus is recognized by antivirus from the unique identity.

2. Virus Duplicating Code

A program can’t be mentioned as a computer virus if it can’t duplicate itself. So this is one of the main structures of computer virus.

3. Protection and defend code

This code is needed by virus to deceive antivirus program. It can be done in many ways: encrypting the virus file, invisible the virus’s process on computer, or showing a redirecting message to prevent the user to open the antivirus program.

4. Manipulating code

The function of this code is to delete files, execute certain applications in order to steal or send data to an e-mail.

Because of the extraordinary development of computer technology, the variant of computer virus is going to be a huge in amount. Therefore, protect your PC with the latest antivirus and keep it update periodically, and not to send malicious data to your lovely computer.