Computer viruses are malicious programs that can damage systems and erase data. There are different types like viruses, worms, and Trojan horses. Viruses piggyback on other programs to replicate, worms use networks to spread, while Trojans masquerade as useful programs but have hidden harms. Signs of infection include slow performance, crashes, and missing files. Regular antivirus updates, secure practices like avoiding untrusted sources can help prevent damage from viruses.

1. www.oeclib.in
Submitted By:
Odisha Electronics Control Library
Seminar
On
Computer Virus

2.  Introduction
 What is Computer Virus
 Types of Infection
 Viruses
 E-mail viruses
 Worms
 Trojan horses
 Types of Computer Virus
 Difference between Virus and Worm
 Signs of a Computer Virus
 Preventions
 Top Seven Antiviral Program
 Conclusion
 Reference

3. A virus is a program
designed by a computer
programmer (malicious
hacker) to do a certain
unwanted function.

4.  Computer virus refers to a program which
damages computer systems and/or destroys or
erases data files.

5.  VIRUSES
 E-MAIL VIRUSES
 WORMS
 TROJAN HORSES

6. A virus is a small piece of
software that piggybacks
on
real programs.
2 main characteristics of
viruses
 It must execute itself.
 It must replicate itself.

7.  Moves around in e-mail messages.
 Usually replicate itself by automatically
mailing itself to dozens of people in the
victim’s email address book.
 Example “MELISSA VIRUS”
 Example “I LOVE YOU VIRUS”

8. Melissa virus spread in Microsoft Word
documents sent via e-mail.
How it works ?
 Created the virus as word document
 Uploaded to an internet newsgroup
 Anyone who download the document and
opened it would trigger the virus.
 Send friendly email messages to first 50 people
in person’s address book.

9.  Melissa Virus was the fastest spreading virus
ever seen.
 Forced a number of large companies to shut
down their e-mail systems.

10.  Contained a piece of code as an attachment.
 Double Click on the attachment triggered the
code.
 Sent copies of itself to everyone in the victim’s
address book
 Started corrupting files on the victim’s
machine.

11.  Small piece of software that
uses computer networks
and security holes to
replicate itself.
 Copy of the worm scans the
network for another
machine that has a specific
security hole.
 Copy itself to the new
machine using the security
hole and start replicating.
 Example “CODE RED”

12.  A simple computer
program
 It claim to be a game
 Erase your hard disk
 No way to replicate
itself.

13.  Time Bomb
 Logical Bomb
 Boot Sector Virus
 Macros Virus
 Script Virus

14.  Time Bomb
A time bomb is a virus program that performs
an activity on a particular date .
 Logical Bomb
A logical bomb is a destructive program that
performs an activity when a certain action has
occurred.

15.  Boot Sector Virus
A boot sector virus infects boot sector of
computers. During system boot, boot sector
virus is loaded into main memory and destroys
data stored in hard disk.

16.  Macros Virus
A macro virus is associated with application
software like word and excel. When opening
the infected document, macro virus is loaded
into main memory and destroys the data stored
in hard disk.
 Script Virus
Commonly found script viruses are written
using the Visual Basic Scripting edition (VBS)
and the JavaScript programming languages.

17.  The difference between a worm and a virus is
that a virus does not have a propagation
vector. i.e., it will only effect one host and does
not propagate to other hosts.
 Worms propagate and infect other computers.
Majority of threats are actually worms that
propagate to other hosts.

18.  Computer viruses cause a huge amount of
damage worldwide.
 Damages from just one virus (The I Love You Virus)
are estimated at $10 billion dollars. It is also
estimated that 45 million people worldwide were
affected.
 Costs come from restoring damaged systems,
replacing lost information, steps taken to
prevent attacks and steps taken to prepare to
recover from attacks.

19.  Jason, a 16 year old honor student, wrote a
computer virus that causes 4 billion dollars of
damage and impacted countless home and
business computers. The authorities traced the
virus to him. Jason says that he is very sorry
and didn’t mean for it to get so out of hand. He
said he was just fooling around to see if he
could do it.

20.  Computer runs slower then 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)

21.  Updates
 Anti-Viruses
 More secure
operating systems
e.g. UNIX

22.  Kespersky Antivirus
 Data fellows E-Plot
 Mcafee Antivirus
 Symantec Norton Antivirus
 Bit Defender 2010
 Quick Heal Antivirus
 ESaSS ThunderBYTE

23.  Be aware of the new infections out there.
 Take precaution measures.
 Always backup your data.
 Keep up-to-date on new Anti virus software.
 Simply avoid programs from unknown
sources.

24.  www.google.com
 www.wikipedia.com
 www.oeclib.in