This document discusses the history and types of computer viruses. It begins by describing basic types of viruses like Trojan horses, worms, and email viruses. It then defines types of viruses like boot sector viruses, program viruses, multipartite viruses, and others. The document outlines some signs that a computer may be infected. It provides examples of notable viruses from the 1980s onward like the Brain virus, Melissa virus, Love Bug virus, and others. It discusses prevention methods like using antivirus software and being cautious of emails and attachments. Overall, the document provides a comprehensive overview of the development of computer viruses and methods to protect against viruses.

1. ComputerComputer
VirusesViruses
BY: SURYA PRAKASHBY: SURYA PRAKASH
ANANTH INTERNATIONAL SCHOOLANANTH INTERNATIONAL SCHOOL

2. 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 by usingvirus that copies and multiplies itself by using
computer networks and security flawscomputer networks and security flaws
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

3. Types of VirusesTypes of Viruses
Boot Sector VirusBoot Sector Virus

Infects the boot or MBR of diskettes and hard drives through theInfects the boot or MBR of diskettes and hard drives through the
sharing of infected disks and pirated software applicationssharing of infected disks and pirated software applications

Once your hard drive is infected all diskettes that you use in yourOnce your hard drive is infected all diskettes that you use in your
computer will be infectedcomputer will be infected
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

4. Types of VirusesTypes of Viruses
Stealth VirusStealth Virus

Disguises itself to prevent from being detected by antivirusDisguises itself to prevent from being detected by antivirus
softwaresoftware

It alters its file size or conceals itself in memoryIt alters its file size or conceals itself in memory
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

5. 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

7. 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
The Jerusalem VirusThe Jerusalem Virus
-had bugs that re-infected programs that were already infected-had bugs that re-infected programs that were already infected

8. 1988: Robert Morris made a worm that invaded ARPANET computers1988: Robert Morris made a worm that invaded ARPANET computers
- disabled 6,000 computers on the network by overflowing their memory banksdisabled 6,000 computers on the network by overflowing their memory banks
with copies of itselfwith copies of itself
1991:1991: Norton Anti-Virus softwareNorton Anti-Virus software
1999:1999: "Melissa" virus"Melissa" virus
-infected thousands of computers very fast by sending copies of itself to 50-infected thousands of computers very fast by sending copies of itself to 50
names in the address book on Outlook e-mailnames in the address book on Outlook e-mail
- Led to an estimated $80 million in damage and record sales of anti-virusLed to an estimated $80 million in damage and record sales of anti-virus
products.products.
2000:2000: "I Love You" virus"I Love You" virus
-was sent by email and infected 10 % of computers in only one day-was sent by email and infected 10 % of computers in only one day
-created by a young Filipino computer student who did not get punished-created by a young Filipino computer student who did not get punished
because then the Philippines had no laws against hacking which led to thebecause then the Philippines had no laws against hacking which led to the
European Union's global Cybercrime Treaty.European Union's global Cybercrime Treaty.
2001:2001: "Nimda" virus (days after 9/11)"Nimda" virus (days after 9/11)
-had 5 ways of infecting systems-had 5 ways of infecting systems

9. 20042004

MyDoom spreads through emails and file-sharing software fasterMyDoom spreads through emails and file-sharing software faster
than any previous virus or worm.than any previous virus or worm.
Allows hackers to access the hard drive of the infected computer.Allows hackers to access the hard drive of the infected computer.

An estimated one million computers running Windows areAn estimated one million computers running Windows are
affected by the fast-spreading Sasser computer worm.affected by the fast-spreading Sasser computer worm.
The worm does not cause irreparable harm to computers or data,The worm does not cause irreparable harm to computers or data,
but it does slow computers and cause some to quit or reboot withoutbut it does slow computers and cause some to quit or reboot without
explanation.explanation.
20062006

Discovery of the first-ever malware trojan horse for Mac OS XDiscovery of the first-ever malware trojan horse for Mac OS X
20082008

Torpig is a Trojan horse which affects Windows, turning off anti-Torpig is a Trojan horse which affects Windows, turning off anti-
virus applications.virus applications.
It allows others to access the computer, modifies data, stealsIt allows others to access the computer, modifies data, steals
confidential information and installs malware on the victim'sconfidential information and installs malware on the victim's
computer.computer.
20092009

Conficker infects anywhere from 9 to 15 million Microsoft serverConficker infects anywhere from 9 to 15 million Microsoft server
systems.systems.

French air force, Royal Navy warships and submarines,French air force, Royal Navy warships and submarines,
Sheffield Hospital network, UK Ministry of Defence, GermanSheffield Hospital network, UK Ministry of Defence, German
Bundeswehr and Norwegian Police were all affected.Bundeswehr and Norwegian Police were all affected.

10. 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

11. MelissaMelissa
Another virus that fired up the media was Melissa, a Word macroAnother virus that fired up the media was Melissa, a Word macro
virus.virus.
When people received the host Word document via email andWhen people received the host Word document via email and
opened it, the virus sent a copy of itself to the first 50 people in theopened it, the virus sent a copy of itself to the first 50 people in the
victim's address book.victim's address book.
Named after a topless dancer in Florida, the Melissa virus crashedNamed after a topless dancer in Florida, the Melissa virus crashed
the email servers of corporations and governments in differentthe email servers of corporations and governments in different
spots around the world.spots around the world.
The Computer Emergency Response Team, set up after RobertThe Computer Emergency Response Team, set up after Robert
Morris mucked up the Internet with his worm in 1988, estimated thatMorris mucked up the Internet with his worm in 1988, estimated that
the virus hit 100,000 computers in its first weekend.the virus hit 100,000 computers in its first weekend.
David L. Smith posted the infected file to an alt.sex usenet groupDavid L. Smith posted the infected file to an alt.sex usenet group
using a stolen AOL account. Initially he entered a plea ofusing a stolen AOL account. Initially he entered a plea of
innocence, but after being confronted with a maximum sentence ofinnocence, but after being confronted with a maximum sentence of
40 years in prison, he eventually pled guilty and received a much-40 years in prison, he eventually pled guilty and received a much-
reduced sentence.reduced sentence.

12. Love You, Love BugLove You, Love Bug
By almost any measure, the so-called Love Bug was the mostBy almost any measure, the so-called Love Bug was the most
damaging and costly virus ever. I don't know who comes updamaging and costly virus ever. I don't know who comes up
with these whack figures, but according to Reuters the bugwith these whack figures, but according to Reuters the bug
cost the world $15 billion in lost productivity.cost the world $15 billion in lost productivity.
The Love Bug spread far faster than Melissa. Unlike Melissa,The Love Bug spread far faster than Melissa. Unlike Melissa,
it would mail itself to everyone in your Outlook address bookit would mail itself to everyone in your Outlook address book
-- most of whom would probably be delighted to read about-- most of whom would probably be delighted to read about
how you love them -- not just the first fifty. Moreover, it wouldhow you love them -- not just the first fifty. Moreover, it would
gobble up certain media files stored on your hard drive.gobble up certain media files stored on your hard drive.

13. 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.

14. 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

15. THANKTHANK
YOUYOU