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Computer viruses and their effects on your pc

Computer Viruses and their Effects on your PC

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Table of Contents

What is a Virus? 1









A virus is an independent program that reproduces itself. It can attach itself to other programs and make copies of itself (i.e., companion viruses). It can damage or corrupt data, or lower the performance of your system by using resources like memory or disk space. A virus can be annoying or it can cost you lots of cold hard cash. A virus is just another name for a class of programs. They do anything that another program can. The only distinguishing characteristic is the program has ability to reproduce and infect other programs. Is a computer virus similar to a human virus? Below is a chart that will show the similarities.

Comparing Biological Viruses & Human Viruses

Human Virus Effects Computer Virus Effects

Attack specific body cells' Attack specific programs (*.com,*.exe)

Modify the genetic information of a cell other

than previous one.Manipulate the program:

It performs tasks.

New viruses grow in the infected cell itself. The infected program produces virus programs.

An infected program may not exhibit symptoms for a while. The infected program can work without error for a long time.

Not all cells with which the virus contact are infected. Program can be made immune against certain viruses.

Viruses can mutate and thus cannot clearly be diagnosed. Virus program can modify themselves & possibly escape detection this way.

Infected cells aren't infected more than once by the same cell. Programs are infected only once by most viruses.

There are many ways a virus can infect you system. One way is, if the virus is a file infecting virus, when you run a file infected with that virus. This particular kind of virus can only infect if YOU run the program! This virus targets COM and EXE files, but have also been found in other executable files. some viruses are memory resident which will infect every file run after that one. Other are "direct action" injectors that immediately infect other files on your hard drive then leave. Another way viruses infect your system is if they are polymorphic. Polymorphism is where the virus changes itself with every infection so it is harder to find. Also, virus writers have come up with a virus called a multipartite virus. This virus can infect boot sectors and the master boot record as well as files therefore enables it to attack more targets, spread further and thus do more damage.

A computer virus can be spread in many different ways. The first way is by a person knowingly installing a virus onto a computer. Now the computer is infected with a virus. The second way is inserting your disk into an infected computer. The infected computer will duplicate the virus onto your disk. Now your disk is a virus carrier. Any computer that comes in contact with this disk will become infected. For example, I once caught a virus from Cochise College by copying two non-infected disks, the computer was infected. What if my friend borrows an infected disk? Your friend's computer will most likely become infected the instant that he/she uses your disk into a computer. The third way, is the Internet. A lot of programs on the Internet contain live viruses. However, there seems to be countless numbers of ways to become infected. Every time you download a program from somewhere or borrow a disk from a friend, you are taking a risk of getting infected.

Computer software bought in stores have been know to carry viruses. "How? CD-ROMS are non-recordable?" A virus may be installed into a computer at the time of manufacturing. In September of 1996, the September edition of Microsoft SPCD has a file infected with a virus called "Wazzu". Watch out for SIA\MKTOOLS\CASE\ED3905A.DOC. Microsoft aided the spread of Wazzu by distributing a Wazzu-infected document on the Swiss ORBITconference CD, and keeping an identical copy of the infected document on it's Swiss Website for at least five days after being notified of the problem. It is noted, by Microsoft records , that over 2 million of the infected CD's were sold. The CD's were replaced on a recall from Microsoft, however: this aided the spread of the Wazzu Virus.


The major damages can vary, but here are the most common:

A. Fill up your P.C. with Garbage:

As a virus reproduces, it takes up space. This space cannot be used by the operator

As more copies of the virus are made, the memory space is lessened.

B. Mess Up Files:

Computer files have a fixed method of being stored. With this being the case, it is very easy for a computer virus to affect the system so some parts of the accessed files cannot be located.

C. Mess Up FAT:

Fat (File Allocation Table) is the method used to contain the information required about the location of files stored on a disk. Any allocation to this information can cause endless trouble

D. Mess Up The Boot Sector:

The boot sector is the special information found on a disk. Changing the boot sector could result in the inability of the computer to run.

E. Erase The Whole Hard Drive/ Diskette:

A virus can simply format a disk. This will cause you to lose all of the data stored on the formatted disk.

F. Reset The Computer:

Virus can reset your computer. Normally, the operator or user has to press a few keys. The virus can do this by sending codes to the operating system.

G. Slowing Things Down:

The object of this virus can slow down the running line of a program. This causes a computer with 100 megahertz to act like a computer with 16 megahertz. That is why a 486 or 586 computer can slow down and run as if it were a 286. As I would call it "Turtle Speed".

H. Redefine Keys:

The computer has been programmed to recognize certain codes with the press of certain keys. For Example: When you press the letter T, your computer puts a T on your display. A virus can change the command. Imagine if every time you pressed the T, your computer would format your hard drive.

I. Lock The Keyboard:

Redefining all the keys into an empty key. Then the user cannot use the keyboard to input any data.

People are often telling me I am paranoid of viruses. Some forms of paranoia are healthy. When it comes to securing your system from viruses, trust no one, not even your mother-when you change disks with her, that is. Thank god for the invention of Anti-Virus Software. Anti-Virus Software is a program that can protect your PC from a virus. They can also remove a virus, once it is detected. However, there are thousands of viruses in existence. And finding a consistant virus scanning program can be rough. I have read many articles on popular virus scanning programs. I have found the top two virus scanning programs to be:

#1.) McAfee Virus Scan

#2.) Norton Anti-Virus

Both of these programs can prevent a virus from entering your computer. If one sneaks past, then you will have a choice to delete the file, clean the virus or move the virus. I would highly suggest you to check out these programs and test them.


Remember, one virus can shred many years of work on your computer. Protect yourself and always, use an Anti-Virus Program.

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