This document provides an overview of computer viruses and antivirus software. It defines a computer virus as a small program that can alter how a computer operates without the user's permission or knowledge. It then describes common types of viruses and how antivirus software works to identify and remove viruses using a virus dictionary. The document concludes with symptoms of an infected computer and precautions users should take like regularly scanning with antivirus software and keeping other software updated.
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Contents:
•What is Computer virus?
•Types of Viruses
•Introduction to Antivirus Program
•How an Antivirus works?
•What to do when suspecting virus attack?
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What is a Computer Virus?
• A computer virus is a small program written to alter the way a
computer operates, without the permission or knowledge of the
user. With an ability to replicate itself, thus continuing to spread.
Also, known as Malicious Software, a program that can cause
damage to a computer.
• The computer viruses can damage or corrupt data, modify existing
data, or degrade the performance of the system by utilizing
resources such as memory or disk space.
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Classification of Computer Viruses:
•Boot sector virus
•Master Boot Record (MBR) virus
•File infector virus
•Multipartite virus
•Macro virus
In addition to Computer viruses, there are
two more types of malicious software.
These are :
Worms and Trojans
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Anti-virus Software
•An antivirus software is a computer program that identify and
remove computer viruses, and other malicious software likeWorms
and Trojans from an infected computer. Not only this, an antivirus
software also protects the computer from further virus attacks.
•We should regularly run an antivirus program to scan and remove
any possible virus attacks from a computer.
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How an Antivirus works
Using dictionary Approach:
The antivirus software examines each and every file in a computer and
examines its content with the virus definitions stored in its virus
dictionary.
A virus dictionary is an inbuilt file belonging to an antivirus software that
contains code identified as a virus by the antivirus authors.
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Some of the symptoms of an infected computer:
•Folder Options disappears from the Tools. Now, hidden files cannot
be viewed. Changing registry values has no effect.
•Regedit doesn’t works, when you try to invoke it from the RUN box
•Task Manager has been disabled by Administrator.
•Command prompt doest open, if it does closes suddenly.
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General precautions you should take
•When inserting removable media (floppy, CD, flash drive etc.) scan the whole device
with the antivirus software before opening it.
•If you have internet access, make sure you use internet security software.
•Get Windows updates.
•From time to time, update your installed software to their latest version. E.g. (MS
Office, Adobe Reader, java, Flash player etc.)