1. COMPUTER
*VIRUS *
Compiled By:
Sanmitha Rao
B.Sc 4th sem
Karnatak Science College Dharwad 1

2. CONTENTS
 Introduction
 Origin of Viruses
 Symptoms of virus attack
 General Virus Types
 Prevention is the best cure
 Working of antivirus software
 Practice safe Computing
Karnatak Science College Dharwad 2

3. What is a virus?
 Virus is a Computer program like any other
Program
 It gives Instructions to your computer to do
the things which you don’t want it to do.
 It spreads.
 It can be destructive.
 It could format your hard drive boot sector
or delete your files and render your machine
inoperable.
Karnatak Science College Dharwad 3

4. *ORIGIN *
 People normally create viruses by writing a
code .
 Generally people create viruses just for thrill
or fun.
 In early days viruses were pieces of code
attached to a program.
 There are estimated 30,000 viruses, over 300
viruses are created each month.
 First virus was created to show loopholes in
software.
Karnatak Science College Dharwad 4

5. Symptoms of Virus attack
 Computer runs slower than usual
 Computer no longer boots up
 Screen sometimes flicker
 PC speaker beeps periodically
 System crashes for no reason
 Files /directories sometimes disappear
 Denial of Service (Dos)
Karnatak Science College Dharwad 5

6. TYPES OF VIRUSES
1. Boot Sector Virus
2. Macro Virus
3. Multipartite Virus
4. Polymorphic Virus
5. E-mail Viruses
6. Worms
7. Trojan horses etc.
Karnatak Science College Dharwad 6

7.  Traditional Virus
 Infect the boot on floppy disks and hard disks.
 By putting its code in the boot sector virus can guarantee it
gets executed.
 Load itself into the memory and it is able to run whenever
the computer is on.
Karnatak Science College Dharwad 7

8.  Written using a simplified programming language
these viruses can effect your Microsoft applications
like word and excel
 A document infected with the Macro Virus generally
modifies a pre-existing commonly used command (such
as save) to trigger its payload upon execution of that
command.
Karnatak Science College Dharwad 8

9.  This can infect both your files and boot sector
 It can infect thousands of times to your system
before it is caught.
 It is a dangerous virus.
Karnatak Science College Dharwad 9

10.  Changes code whenever it passes to
another machine.
Karnatak Science College Dharwad 10

11.  It moves around in the email messages.
 Usually replicates itself by automatically
mailing itself to the dozens of people in the
victims e-mail address book.
Karnatak Science College Dharwad 11

12.  It has the ability to copy itself from
machine to machine.
 Eat up storage space and slows down
the computer.
 Normally move around and infect other
machine through computer networks.
 But worms don’t alter or delete files.
Karnatak Science College Dharwad 12

13.  It is basically a computer program that
claims to do one thing, but instead it
damages the computer.
 It can capture information from your
system such as user name and password or
could allow a malicious hacker to remotely
control your system.
 It has no way to replicate automatically.
Karnatak Science College Dharwad 13

14. PREVENTION IS THE BEST
CURE
1. Install a virus protection software.
2. Run a secure operating system like Unix or NT.
3. Avoid programs from unknown sources.
4. Disable floppy disk booting.
5. Macro virus protection is enabled in all Microsoft
applications.
6. Never double click on the attachment that comes as an
executable that arrives as an email attachment.
Karnatak Science College Dharwad 14

15. Working of Antivirus Software
 There are two ways in which a antivirus
software works-scanning software kooks
for a virus,scanning software looks for a
unusual virus.
 For a known virus software will look for a
virus signature and will zap it from the
system.
 For an unknown virus the software
quarantines the questionable program and
will inform you about what the program
may be trying to do.
Karnatak Science College Dharwad 15