1. ~Computer Virus~
The things you MUST know
Brought to You By
Sumanta Majumdar
Dept. Of Electrical Engg.
2010,GNIT
http://powerpointpresentationon.blogspot.com/

2. Introduction
• About Virus
• Computer virus have become
today’s headline news.
• With the increasing use of the
internet, it has become easier for
virus to spread.
• Virus show us loopholes in
software.
• Most virus are targeted at the MS
Windows OS

3. ~ Classifying
Computer Virus ~
• A program designed to attach • File Virus: A computer virus that
itself to a file, reproduce, and infects executable files, that is
programs with exe filename
spread from one file to extensions
another, destroying data, • Payload: The disruptive
displaying an irritating instructions or message delivered
message, or otherwise by a computer virus. Payloads can
disrupting computer range from just being annoying to
operations. destroying data and files on a
computer system.
• Boot Sector Virus: A computer
virus that infects the sectors on a
disk that contain the data a
computer uses during the boot
process. The virus spreads every
time the infected disk is in the
computer when it boots.
• Macro Virus: A computer virus
that infects the macros that are
attached to documents and
spreadsheets.
• Trojan Horse: A computer
program that appears to perform
one function while actually doing
something else, such as inserting a

4. * Virus through the
Internet *
Today almost 87% of all viruses
are spread through the internet.
Transmission time to a new host
is relatively low, on the order
of hours to days
“Latent virus”

5. Symptoms of Virus Attack
• Computer no longer boots up.
• Screen sometimes flicker.
• Computer runs slower then usual.
• PC speaker beeps periodically.
• System crashes for no reason.
• Files/directories sometimes disappear.
• Denial of service (dos)….. & Many More.

6. ~Computer Virus~
How They Spread
• A virus runs first when a legitimate • Unfortunately, the virus has now
program is executed. reproduced itself, so two programs
• The virus loads itself into memory are infected.
and looks to see if it can find any • The next time either of those
other programs on the disk. programs gets executed, they infect
• If it can find one, it modifies it to add other programs, and the cycle
the virus's code to the new program. continues.
• Then the virus launches the "real • When the infected program
program“. o is distributed by
• The user has no way to know that  floppy disk
the virus ever ran.  uploaded to a bulletin board
 zipped and delivered as an
executable.
• then other programs get infected.

7. ~Computer Virus~
How To Prevent Them
• Security features keep viruses away.
• Buy virus protection software.
• Avoid programs from unknown sources (like
the Internet).
• Stick with commercial software purchased on
CDs.

8. ~Computer Virus~
How To Prevent Them
• With E-mail viruses
o defense is personal discipline
 Never double-click on an attachment that contains
an executable program
 Attachments that come in as
 Word files (.DOC), spreadsheets (.XLS), images (.GIF
and .JPG), etc., are data files
 and they can do no damage

9. ~Computer Virus~
How To Prevent Them
• Don’t victimize yourself
o learn where to find legitimate information on
hoaxes, myths etc.
 do not forward warnings if you haven’t personally
checked them out!

10. ~Computer Virus~
How To Prevent Them
Don’t fall for the
• "False Authority Syndrome”
o Most people who claim to speak with authority
about computer viruses have little or no genuine
expertise.
 The person feels competent to discuss viruses because of
 his job title,
 because of expertise in another computer field,
 simply because he knows how to use a computer.

11. ~Computer Virus~
How To Prevent Them
• E-mail is clearly the predominant vulnerability
point for viruses
o Current viruses are spread via security holes in
Microsoft Outlook and Outlook Express
 Free patches are available from Microsoft to address these
problems
 many people are reluctant to apply them.
• First, update your system with Windows Update
and Office Update
o or, buy a Mac
• Buy virus protection software

12. ~Computer Virus~
How To Scan?

13. ~Computer Virus~
Anti-Virus Is Scanning

14. ~Computer Virus~
Finding Out A Virus

15. Computer Virus
• Acknowledgement
• My special thanks goes to Sri Supriyo Ghosh
(Dept. of BCA,Techno India, Sec. V) for
helping & suggesting me about different kind
of computer viruses & their characteristics.

16. Computer Virus
• Be Original Kill Piracy.