Force Byte
Computer Virus - Introduction and Prevention (1)

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The last series of "Useful Tips on Computer Usage" is very useful for your work, isn't it? In fact, getting to know ways of protecting your computer is as important as getting to know how to use the computer. For example, if your computer is frequently infected by viruses, which make it hanged or corrupt data, your daily work will inevitably be interrupted a lot.

Luckily, the chance of being harassed by computer virus is minimal in our office, because the virus prevention and support team of ITB has installed the most advanced anti-virus software in our computers. In addition, they will download the updated virus definition file and install it into our computers whenever needed, so most virus infection can be prevented effectively. Besides, they will collect the latest information about viruses and alert us about them by e-mail.

But all these measures are not sufficient to guarantee our computers not to be infected by viruses totally. If we still download files from suspicious websites or open unknown files from e-mail, it is highly susceptible that our computers are prone to virus infection or hacker's attack.

In order to arouse your awareness about virus infection, I am going to brief you on the virus types, their ways of infection, and the precautions you can take in this and next issues.

First of all, there are about eight common types of computer viruses. This time I will introduce the first four types to you.

Type	Infection Channel
1. File Infector Virus	This virus type is always attached to the executable files with extensions of .EXE and .COM. Upon the file execution, the attached virus will also be activated. It will then start duplicating itself and destroying or tampering with data in your computer.
2. Boot Strap Sector Virus	This virus type primarily spreads by floppy disk. It will hide in the boot sector of the floppy disk. If you don't know that this floppy disk is infected and use it to boot up your computer, the virus inside will be loaded into the system memory and the boot sector of the hard disk. It will then make changes to the system boot sector and move some programmes away. If these programmes are essential for booting process and the system cannot find them, your computer will eventually be unable to start up.
3. Macro Virus	Macro Virus is developed from the macro functions accompanied with such application as MS Word, MS Excel, etc. Actually this virus type is in the form of a Word document or template. If the user opens it, the hidden virus will infect the "Normal.dot" (the default template) of MS Word. Subsequently all open documents in MS Word will be infected.
4. Multi-Partite Virus	This virus type has the characteristics of both the file infector virus and the boot strap sector virus. In other words, it will be loaded into the system memory and infect the boot sector. In addition it will infect all types of executable files. You may say that it incorporates all the strong points of these two virus types and is therefore more destructive.

After all, in order to prevent your computer from being infected, you'd better not open executable files or data files from unknown sources and make sure that no unknown disk has been inserted into the floppy drive when you switch on the computer; otherwise, your computer will be liable to virus infection and may not function properly.

Hope you get an idea of what virus is all about. We will discuss four other types of viruses next time.

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