This document provides an overview of computer viruses, including their history, concepts, symptoms, types, and preventive measures. It discusses how the first computer virus was created in 1981 and that viruses now number in the millions. Various types of viruses are defined, such as boot sector viruses, browser hijackers, file infectors, and polymorphic viruses. Symptoms of a virus include slow performance, crashes, and file loss. The document concludes with recommendations to use reputable download sources, firewalls, avoid suspicious emails, and install antivirus software to prevent virus infections.

1. COMPUTER
VIRUSES
Presented by:
Aditi Ambekar
Angela Mary Binoy
Annies Minu SathiyaSeelan

2. SICK OF COMPUTER
VIRUSES?
What they are…
Where they come from…
Why they are here…

3. Index
1. History
2.Concept
3. Symptoms
4. Types Of Infections
6. Types Of Viruses
7.Preventive Measures

4. History
•The first computer virus was called
“Creeper.”It was invented in the early
1970’s.Since then, millions of viruses
have been invented.
•The first known computer virus was
written in 1981 by a man named Rich
Skrenta.This virus was termed Elk
Cloner, and was the first computer
virus to appear outside the computer
where it was created in.

5. Everyone who owes a computer
might heard a lot about computer
viruses….
Virus +
DEATH

6. What is a Computer Virus?
A Computer Virus is a program
that can copy itself and infect a
computer without the
permission or knowledge of
the user.
A Computer Virus has 2 major
characteristics: the ability to
replicate itself, and the ability
to attach itself to another
computer file...

7. SYMPTOMS
The following are a few Symptoms that your
computer might have a virus:
• Slow response and slow program execution.
• Random hard drive crashes and restarts.
• Distorted graphics and text.
• Files that have mysteriously vanished.
• Extensive pop-up ads.
• Inability to open files with existing passwords.

8. Types Of Infections
Malware
Viruses
Worms
Trojan
Horses

9. Types Of Computer Viruses
1.
2.
3.
4.
5.
6.
7.
8.
9.
Boot Sector Virus.
Browser Hijacker.
Direct Action Virus.
File Infector Virus.
Macro Virus.
Multipartite Virus.
Polymorphic Virus.
Resident Virus.
Web Scripting Virus.

10. Boot Sector Virus
• Boot sector virus infects
the boot sector of a
HDD or FDD. These are
also memory resident in
nature. As soon as the
computer starts it gets
infected from the boot
sector.
Cleaning this type of
virus is very difficult

11. Browser Hijacker
•Alters the search and error page of a
browser and redirects the user to its own
page.

12. Direct Action Virus
•They load with the host program into
computer’s memory.
•They can be crafted with relative ease.

13. File Infector Virus
• This type of virus normally infects program files
such as .exe, .com, .bat. Once this virus stays in
memory it tries to infect all programs that load
on to memory.

14. Macro Virus
• These type of virus infects word, excel,
PowerPoint, access and other data files. Once
infected repairing of these files is very much
difficult.

15. Multipartite Virus
• A hybrid of Boot and Program/file viruses. They
infect program files and when the infected program
is executed, these viruses infect the boot record.
When you boot the computer next time the virus
from the boot record loads in memory and then
start infecting other program files on disk

16. Polymorphic Virus
• A virus that can encrypt
its code in different
ways so that it appears
differently in each
infection. These viruses
are more difficult to
detect.

17. Resident Virus
•
•
•
•
Hides within the computers memory.
It activates whenever the OS loads or operates.
This virus may be pernicious.
It is of 2 types:
Fast Infector.
Slow Infector.
• Removal of this virus is bit tricky.
• It may be designed to block the actions of Anti
Virus programs.

18. Web Scripting Virus
There are few website that execute complex code
with the purpose to provide interesting content
,these codes often get exploited and due to this a
virus becomes able to infect a machine and to
take actions on a machine via website. This
particular virus is called web scripting virus

19. Preventive Measures
•Be Sure to download only from
Reputable Websites.
•Install a Quality Firewall
Program.
•Do not open Suspicious Emails
or Attachment.
•Most Importantly make sure
that you have a good Anti Virus
program installed.

21. CONCLUSION

22. THANK YOU!