Contents

1. Computer security threats. Viruses. 3

1.1 Defining viruses and computer worms 3

1.2 History of viruses. 4

1.3 Who writes computer viruses? 7

1.4 To whose advantage hackers write computer viruses? 9

1.5 A Legal Notice. 11

1.6 Types of Computer Security Threats 12

2. Computer antivirus software. 20

2.1 Best antivirus software. 20

2.2 Internet Security. Firewalls. 22

Conclusion. 24

References and sources. 25

Introduction

At the present stage of our society it is obviously evident that every person should remember not only about his (her) own safety, but about the safety of his (her) private computer, too. In the modern world almost every person uses a computer every day, but does not mind about various dangers he (she) can face.

Thousands of different viruses and worms attack millions of computers all over the world every day; a lot of huge computer systems are getting over control every hour and may be at this moment you are losing the most important information you have on your PC.

So it is definitely evident that this topic is very important. In this work some attempts to clarify the description of the word “virus” have been made and the problem of choosing the right antivirus software has been chosen.

The purpose of the research work is to study viruses and how to get rid out of them. The object of the research is antivirus software; the subject is the ability of the system to fight the present-day most dangerous viruses.

In order to achieve this goal, it is necessary to fulfill several tasks:

• Firstly, to investigate the issue of computer viruses from the theoretical point of view, i.e. to study the history of the first viruses, examine types of viruses and what harm they can cause.

• Secondly, to give the general description of advanced computer antivirus systems.

According to the goals and tasks, the structure of the work is the following: In the first chapter theoretical issues related to the definition of the word “virus” have been studied. The second chapter is the analysis of advanced computer systems.

1. Computer security threats. Viruses.

1. Defining viruses and computer worms

We live in the digital world, where computers are not just an ordinary thing anymore but a “necessity” to our everyday live. You might use a computer daily or once in a blue moon – you never know when your private information can be attacked.

If you want to be safe you should be aware of all dangers you can face either going out without a hat and a warm coat in cold winter evening or surfing unknown web-sites in the internet without a good antivirus software: in both situations you are lucky to get a dangerous virus that will make you a lot of harm. They differ only in such a way: the illness caused by the biological virus will destroy your health from inside by killing living cells and the computer virus will destroy the health of your personal computer from inside out.

Every one of us knows what a virus is. (” Virus: A microorganism that is smaller than a bacterium that can not grow or reproduce apart from a living cell. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself. It may reproduce with fidelity or with errors (mutations); this ability to mutate is responsible for the ability of some viruses to change slightly in each infected person, making treatment difficult” [1])

And what is called a “computer virus”?

Computer virus is an executable code able to reproduce itself. Viruses are an area of pure programming, and, unlike other computer programs, carry intellectual functions on protection from being found and destroyed. They have to fight for survival in complex conditions of conflicting computer systems. That's why they evolve as if they were alive. [2]

Viruses seem to be the only alive organisms in the computer environment, and their main goal is survival. That is why they may have complex encrypting/decrypting engines, which is indeed a sort of a standard for computer viruses nowadays, in order to carry out processes of duplicating, adaptation and disguise. [3]

It is necessary to differentiate between reproducing programs and Trojan horses. Reproducing programs will not necessarily harm your system because they are aimed at producing as many copies (or somewhat-copies) of their own as possible by means of so-called agent programs or without their help. In the later case they are referred to as "worms".

Meanwhile Trojan horses are programs aimed at causing harm or damage to PC's. Certainly it's a usual practice, when they are part of "tech-organism", but they have completely different functions.

That is an important point. Destructive actions are not an integral part of the virus by default. However virus-writers allow presence of destructive mechanisms as an active protection from finding and destroying their creatures, as well as a response to the attitude of society to viruses and their authors. [4]