2. By: TayyabaBy: Tayyaba
Farooq KhanFarooq Khan
Roll# 41Roll# 41
ComputerComputer
VirusesViruses

3. What is a Computer Virus?What is a Computer Virus?
 A computer virus is a computer program thatA computer virus is a computer program that
can copy itself and infect a computer without thecan copy itself and infect a computer without the
permission or knowledge of the owner.permission or knowledge of the owner.
 One of the first detected virus was the CreeperOne of the first detected virus was the Creeper
virus in the early 70’svirus in the early 70’s

4. Basic Computer VirusesBasic Computer Viruses
 Trojan HorsesTrojan Horses
 appears as interesting program file but when installedappears as interesting program file but when installed
it allows intruders to access and read your filesit allows intruders to access and read your files
 WormsWorms
 virus that copies and multiplies itself byvirus that copies and multiplies itself by
using computer networks and securityusing computer networks and security
flawsflaws
 E-mail VirusesE-mail Viruses
 use e-mail messages to spread which allow it touse e-mail messages to spread which allow it to
automatically forward itself to thousands of peopleautomatically forward itself to thousands of people

5. Types of VirusesTypes of Viruses
 Program VirusProgram Virus
 Becomes active when the program file (usually withBecomes active when the program file (usually with
extensions .BIN, .COM, .EXE, .OVL, .DRV) carrying the virus isextensions .BIN, .COM, .EXE, .OVL, .DRV) carrying the virus is
openedopened
 It then makes copies of itself and will infect other programs onIt then makes copies of itself and will infect other programs on
the computerthe computer
 Multipartite VirusMultipartite Virus
 Hybrid of a Boot Sector and Program virusesHybrid of a Boot Sector and Program viruses
 It infects program files and when the infected program is active itIt infects program files and when the infected program is active it
will affect the boot recordwill affect the boot record

6. Types of VirusesTypes of Viruses
 Polymorphic VirusPolymorphic Virus
 Act like a chameleon, changing its virus signature (binaryAct like a chameleon, changing its virus signature (binary
pattern) every time it multiples and infects a new filepattern) every time it multiples and infects a new file
 Macro VirusMacro Virus
 Programmed as a macro embedded in a document, usuallyProgrammed as a macro embedded in a document, usually
found in Microsoft Word and Excelfound in Microsoft Word and Excel
 Once it gets in to your computer, every document you produceOnce it gets in to your computer, every document you produce
will become infectedwill become infected
 Relatively new type of virus and may slip by your antivirusRelatively new type of virus and may slip by your antivirus
software if you don't have the most recent version installedsoftware if you don't have the most recent version installed

7. Signs Your Computer is InfectedSigns Your Computer is Infected
 Functions slower thanFunctions slower than
normalnormal
 Responds slowly andResponds slowly and
freezes oftenfreezes often
 Restarts itself oftenRestarts itself often
 See uncommon errorSee uncommon error
messages, distortedmessages, distorted
menus, and dialog boxesmenus, and dialog boxes
 Notice applications fail toNotice applications fail to
work correctlywork correctly
 Fail to print correctlyFail to print correctly

9.  First half of the 70'Late 60,s, early 70,s- "Rabbits" clonedFirst half of the 70'Late 60,s, early 70,s- "Rabbits" cloned
themselves occupied system resources, slowing down the productivity.themselves occupied system resources, slowing down the productivity.
 -"The Creeper" capable of entering a network by itself and transferring a-"The Creeper" capable of entering a network by itself and transferring a
copy of itself to the system.copy of itself to the system.
 Early 80,s-Increasing number of programs written by individuals not byEarly 80,s-Increasing number of programs written by individuals not by
software companies. Programs caused miner viruses called "Trojan horses".software companies. Programs caused miner viruses called "Trojan horses".
 1986'Brain virus' - by Amjad and Basit Farooq Alvi.1986'Brain virus' - by Amjad and Basit Farooq Alvi.
- spread through floppy disks,spread through floppy disks,
- infected boot records and not computer hard drivesinfected boot records and not computer hard drives
 Lahore, Pakistani Brain, Brain-A and UIUC virusLahore, Pakistani Brain, Brain-A and UIUC virus
-took over free space on the floppy disk and hid from detection-took over free space on the floppy disk and hid from detection
”disguised itself by displaying”disguised itself by displaying
the uninfected boot sector on the disk.”the uninfected boot sector on the disk.”
 1987-Lehigh virus1987-Lehigh virus
- the first memory resident file infector that attacked executable files and- the first memory resident file infector that attacked executable files and
took control when a file was openedtook control when a file was opened

10.  20062006
 Discovery of the first-ever malware trojan horse forDiscovery of the first-ever malware trojan horse for
Mac OS XMac OS X
 20082008
 Torpig is a Trojan horse which affects Windows,Torpig is a Trojan horse which affects Windows,
turning off anti-virus applications.turning off anti-virus applications.
 It allows others to access the computer, modifiesIt allows others to access the computer, modifies
data, steals confidential information and installsdata, steals confidential information and installs
malware on the victim's computer.malware on the victim's computer.
 20092009
 Conficker infects anywhere from 9 to 15 millionConficker infects anywhere from 9 to 15 million
Microsoft server systems.Microsoft server systems.
 French air force, Royal Navy warships andFrench air force, Royal Navy warships and
submarines, Sheffield Hospital network, UKsubmarines, Sheffield Hospital network, UK
Ministry of Defence, German Bundeswehr andMinistry of Defence, German Bundeswehr and
Norwegian Police were all affected.Norwegian Police were all affected.

11. Total Number of Viruses by yearTotal Number of Viruses by year
January 1985 1January 1985 1
January 1985 1January 1985 1
January 1987 3January 1987 3
January 1989 6January 1989 6
January 1990 142January 1990 142
January 1991 357January 1991 357
January 1992 1,161January 1992 1,161
January 1993 2,482January 1993 2,482
January 1994 3,687January 1994 3,687
January 1995 5,626January 1995 5,626
January 1996 7,764January 1996 7,764
January 1997 11,037January 1997 11,037
January 1998 16,726January 1998 16,726
January 1999 40,850January 1999 40,850
January 2000 44,000January 2000 44,000
January 2001 48,000January 2001 48,000
January 2002 55,000January 2002 55,000
January 2003 62,000January 2003 62,000

12. Did you know?Did you know?
 One German newspaperOne German newspaper
tragically lost 2,000tragically lost 2,000
pictures from its archive.pictures from its archive.
 The perpetrator turned outThe perpetrator turned out
to be a 23-year-old Filipinoto be a 23-year-old Filipino
computer science studentcomputer science student
who more or lesswho more or less
plagiarized all of his code.plagiarized all of his code.
 The lack of laws in theThe lack of laws in the
Philippines coveringPhilippines covering
computer crimes, he prettycomputer crimes, he pretty
much got away with hismuch got away with his
crime.crime.

13. PreventionPrevention
 Upload and use antivirusUpload and use antivirus
softwaresoftware
 Be aware of the e-mailsBe aware of the e-mails
and attachments youand attachments you
openopen
 Check for updates onCheck for updates on
antivirus softwareantivirus software
regularlyregularly
 Make sure antivirusMake sure antivirus
software is installedsoftware is installed
correctlycorrectly