a brief introduction about computer viruses, their types, how they spread and what precautions should be followed to stay unaffected.

1. 11/7/2013 1Rabia Bibi

2. Rabia bibi
11777
COMPUTER VIRUSES
11/7/2013 2

3. Computervirus:
Is a type of malware, designed to replicate
itself by copying itself into the other
programs stored in a computer. It may cause
a program to operate incorrectly or
corrupting a computer's memory.
11/7/2013 3Rabia Bibi

4. 11/7/2013 4RabiaBibi
Malware:
Software that is written and distributed for
malicious purposes, such as impairing or
destroying computer systems.
Characteristics of computer viruses
They are a piece of program or code.
Executes without any permission or informing to user.
Replicates, and made copies of themselves to spread.
Some types require special command to replicate.
can corrupt and distribute personal info of the user over internet.
They are all men made.

5. 11/7/2013 5RabiaBibi
Symptoms:
• Computer functions slower than normal
• Responds slowly and freezes often.
• Often restarts itself.
• See uncommon error messages, distorted menus,
and dialog boxes.
• Notice applications fail to work correctly.
• Fail to print correctly.

6. 11/7/2013 Rabia Bibi 6
Sundus mukhtar
11800
History of computer virus

7. 11/7/2013 Rabia Bibi 7
1949,
john von Neumann came up with the theory about self-
replicating programs and “creeper” was the first
Virus invented for experimental purpose. 1981
Apple Viruses 1, 2, and 3 are some of the first viruses
in the public domain. Found on the Apple II operating
system, the viruses spread through computer games.
1983
Fred Cohen, defines a computer virus as “a computer
program that can affect other computer programs by
modifying them in such a way as to include a (possibly
evolved) copy of itself.”
1/30/2015 7Sundus mukhtar

8. 11/7/2013 Rabia Bibi 8
1986,
1998,
the first PC virus, codename “The Brain” is released from
Pakistan.
.
StrangeBrew is the first virus to infect Java files.
The Chernobyl virus spreads quickly via .exe files
the virus is quite destructive, attacking not only files but
also a certain chip within infected computers.
2000
Tristate is the first multi-program macro virus; it infects
Word, Excel, and PowerPoint files.
“I Love You” virus appears. It managed to infect millions
of computers in just under a day.
1/30/2015 8Sundus mukhtar

9. 11/7/2013 Rabia Bibi 9
2001
the Code Red virus posed a serious threat to the White House
website. It infected tens of thousands of computers
The same year, the Nimda virus hits the Internet. In the brief
history of computer viruses this is one of the most sophisticated
viruses ever to appear.
2005
March saw the world's first cell phone virus: Commwarrior-A.
The virus probably originated in Russia, and it spread via text
message.
2010
Stuxnet is a computer worm targeting Siemens industrial
software through Microsoft Windows.
1/30/2015 9Sundus mukhtar

10. 11/7/2013 Rabia Bibi 1010ROLL NO: 11742

11. 11/7/2013 Bushra Khan 11
TYPES OF COMPUTER VIRUSES
 Email virus
 Worms
 Trojan horses
 Macro virus
 Logic and time bomb virus
 Boot sector
11
BUSHRA KHAN
ROLL NO: 11742

12. 1/30/2015 Rabia Bibi 12
Email viruses
• Email viruses first started showing up in the
1990s when the use of email became
widespread.
• Email virus is of two types:
• Melissa virus
• ILOVEYOU virus
12
BUSHRA KHAN
ROLL NO: 11742

13. 11/7/2013 Rabia Bibi 13
MELISSA VIRUS
• One of the most impressive viruses to hit
computers was the Melissa virus, which
happened in March 1999.
13
BUSHRA KHAN
ROLL NO: 11742

14. 11/7/2013 Rabia Bibi 14
ILOVEYOU virus
• Another notable email virus was called the
ILOVEYOU virus, which infected computers
on May 4, 2000.
14
BUSHRA KHAN
ROLL NO: 11742

15. 11/7/2013 Rabia Bibi 15
Worms
• A program that makes copies of itself; for
example, from one disk drive to another, or
by copying itself using email or another
transport mechanism.
15
BUSHRA KHAN
ROLL NO: 11742

16. 11/7/2013 Rabia Bibi 16
Types of worms
Email Worms
Instant Messaging Worms
File-sharing Networks Worms
16
BUSHRA KHAN
ROLL NO: 11742

17. 11/7/2013 Rabia Bibi 17
• BOOT SECTOR VIRUS
• LOGIC BOMB VIRUS

18. 11/7/2013 Rabia Bibi 18
Definition
A sector on the computer floppy disk drive, hard drive, or other bootable disk drive
that contains instructs the computer on how to boot from the drive.
There are two kinds of boot sectors - volume boot records and master boot records.
IBM PC disk drives:
IBM PC disk drive have different types of boot sectors
• MBR (master boot record) which is the first sector of a portioned hard drive volume boot
record.
• VBR (volume boot record) which contains partition information at the beginning of each
partition.
1/30/2015 12:03 PM 18Anamhassan

19. 11/7/2013 Rabia Bibi 191/30/2015 12:03 PM Anamhassan 19
Example with the help of diagram:
In this example, the drive has two partitions; each partition contains its own VBR.
When BIOS hands control over to the boot sectors, the MBR takes control and starts
the boot process and refers to the VBR to point it to the partition information. Several
major kinds of boot sectors could be encountered on IBM PC compatible hard
disks, floppy disks and similar storage device.

20. 11/7/2013 Rabia Bibi 20
A boot sector virus is a computer virus that infects a storage device's
MBR. It is not mandatory that a boot sector virus successfully boot the
victim's PC to infect it. As a result, even non-bootable media can
trigger the spread of boot sector viruses. These viruses copy their
infected code either to the floppy disk's boot sector or to the hard
disk's partition table. During start-up, the virus gets loaded to the
computer's memory. As soon as the virus is saved to the memory, it
infects the non-infected disks used by the system.
The propagation of boot sector viruses has become very rare since the
decline of floppy disks.
1/30/2015 12:03 PM 20Anamhassan
What does Boot Sector Virus mean?

21. 11/7/2013 Rabia Bibi 211/30/2015 12:03 PM 21Anamhassan

22. 11/7/2013 Rabia Bibi 22
A logic bomb also called
because all that's left after it detonates is computer
slag, is not the same thing as a virus, although it often
behaves in a similar manner.
WORKING:
It is a piece of computer code that executes a
malicious task, such as:
•Clearing a hard drive
•Deleting specific files
It's secretly inserted into the code of a computer's
existing software, where it lies dormant until that event
occurs.
This event can be either
Positive event
Negative event
SLAG CODE
1/30/2015 12:03 PM 22Anam hassan

23. 11/7/2013 Rabia Bibi 231/30/2015 22
SPEAKER:
AMMARA FAROOQUI
11736

24. 11/7/2013 Rabia Bibi 24

25. 11/7/2013 Rabia Bibi 251/30/2015 25
TROJAN HORSES
VIRUS
• normal computer
programs
• pretends to be a regular
downloadable program
• incapable of replicating
Ammara farooqui

26. 11/7/2013 Rabia Bibi 261/30/2015 26
CONT.
most insidious types is
that the program claims
to rid your computer of
viruses but instead
introduces viruses onto
your computer.
Ammara farooqui

27. 11/7/2013 Rabia Bibi 27
271/30/2015 Ammara farooqui

28. 11/7/2013 Rabia Bibi 28
MACRO VIRUSES
• written in a macro language
• spread as an e-mail virus
• depends on the application
rather than the operating system
1/30/2015 28Ammara farooqui

29. 11/7/2013 Rabia Bibi 29
1/30/2015 29
CONT..
• "infects" a Microsoft Word or
similar application
• causes a sequence of actions
to be performed automatically
Ammara farooqui

30. SPEAKER:
MADIHA AHMED
ROLL NO:
11761
3011/7/2013 MADIHA AHMED

31. 11/7/2013 Rabia Bibi 31
Virus Entrance
Attachment Of Virus
Appearance Of Virus
Execution Or Running Of Effected Program
Computer System Get Effected With Virus
11/7/2013 31MADIHA AHMED

32. 11/7/2013 Rabia Bibi 32
There are literally dozens of ways for
viruses to enter into the computer system.
11/7/2013 32MADIHA AHMED

33. 11/7/2013 Rabia Bibi 33
Virus attaches to its target file or
software present in computer system .
11/7/2013 33MADIHA AHMED

34. 11/7/2013 Rabia Bibi 34
:It can appear in the form of code, scripts, active content, other software and email
attachments.
11/7/2013 34MADIHA AHMED

35. 11/7/2013 Rabia Bibi 35
EXECUTION OR
RUNNING OF
PROGRAM
REPLICATIO
N
11/7/2013 35MADIHA AHMED

36. 11/7/2013 Rabia Bibi 36
11/7/2013 36MADIHA AHMED

37. 11/7/2013 Rabia Bibi 377/11/2013Noor-ul-ainn 37
Anti virus
noor-ul-ainn
roll no:
11 77
3
Noor-ul-ainn7/11/2013

38. 11/7/2013 Rabia Bibi 38
Definition:
• “Antivirus" is protective
software designed to defend your
computer against malicious
software. Malicious software, or
"malware" includes: viruses,
Trojans, key loggers, hijackers,
dialers, and other code that
vandalizes or steals your
computer contents. In order to be
an effective defense, your
antivirus software needs to run in
the background at all times.
7/11/20Noor-ul-ainn 38
P
R
O
T
E
C
T
7/11/2013

39. 11/7/2013 Rabia Bibi 39
Problems:
• One of the most common reasons
for failures or problems in
computers is the lack of antivirus
software, or expired antivirus
software.
• A few examples are provided
below:
• Computer run slowly itself.
• Damage parts of the system or
how the system operates without
the owner's knowledge .
• Be used to steal personal details .
• receiving out unauthorized
messages / emails.
7/11/2013 Noor-ul-ainn 39

40. 11/7/2013 Rabia Bibi 40
anti-virus:
HOW IT WORKS ?
• Anti virus software will
constantly monitor the
activity of all the programs.
• If any program tries to write
data on an executable file
the antivirus software will
flag the program having a
suspicious behavior means
the suspected programs will
be marked as virus.
7/11/2013 Noor-ul-ainn 40

41. 11/7/2013 Rabia Bibi 41
So What Does Antivirus
Software Do?
• Antivirus software is
the "policeman" at the
gate of a computer
system. It protects the
computer from
incoming threats and
seeks out, destroys and
warns of possible
threats to the system.
7/11/2013 Noor-ul-ainn 41

42. 11/7/2013 Rabia Bibi 42
Cont..
New viruses are coming
out all the time. It is the
job of the antivirus
software to keep up
with the latest threats.
This is achieved by daily
updates of the antivirus
data base,its purpose is
to counteract the latest
threats to provide
constant protection.
7/11/2013 Noor-ul-ainn 42

43. 11/7/2013 Rabia Bibi 43
Examples:
• Examples of common antivirus
programs include Norton
Antivirus, Kaspersky Anti-Virus,
and ZoneAlarm Antivirus.
slide 7
43antivirus

44. 11/7/2013 Rabia Bibi 44
11/07/2013
Hira Arshad44

45. 11/7/2013 Rabia Bibi 4511/07/2013Hira Arshad45

46. 11/7/2013 Rabia Bibi 4611/07/2013
Hira Arshad
46

47. 11/7/2013 Rabia Bibi 4711/07/2013
Hira Arshad47

48. 11/7/2013 Rabia Bibi 48
11/07/2013Hira Arshad48

49. 11/7/2013 Rabia Bibi 4911/07/2013HiraArshad49

50. 11/7/2013 Rabia Bibi 50
http://www.makeuseof.com/tag/history-computer-
viruses-worst-today-case-wondering/
 http://inventors.about.com/od/computerviruses/
http://www.howstuffworks.com/virus2.htm
www.buzzle.com/articles/different-types-of-
computer-viruses.html
http://www.computervirusremovalguide.com/a-brief-
look-at-the-history-of-computer-viruses.php
www.makeuseof.com/tag/types-computer-viruses-
watch/
www.webopedia.com/TERM/V/virus.html/

51. 11/7/2013 Rabia Bibi 51