This document discusses computer viruses, including their introduction, etymology, history, types, logic, examples, signatures, and preventive measures. It defines computer viruses as self-replicating programs that infect files and spread. The first paper to use the term "virus" was in 1984, while the first viruses appeared in the early 1970s. Common types include file, macro, and boot sector viruses. Signatures help identify specific viruses, and anti-virus software using signatures and heuristics can detect and remove viruses.

2. INTRODUCTION
• A Computer Virus is actually a computer program
that can increase its own number by replicating
itself and keeps on infecting the other files by
changing their properties continuously.
• It can be sent by various means such as over the
internet, by email, or can be carried on various
storage mediums such as Floppy, Portable Hard
Disks, Pen Drives, Bluetooth, CD's & DVD's etc.

3. ETYMOLOGY
• In 1984 Fred Cohen from the University of
Southern California wrote his paper "Computer
Viruses - Theory and Experiments“. It was the first
paper to explicitly call a self-reproducing program
a "virus", a term introduced by Cohen's mentor
Leonard Adleman.
• The actual term "virus" was first used to denote a
self-reproducing program in a short story by
David Gerrold in Galaxy magazine in 1969 - and
later in his 1972 novel, When HARLIE Was One.

4. HISTORY
• In 1971, The Creeper was the first detected
Virus on ARPANET, the forerunner of internet.
• In 1981, A program called “Elk Cloner” was the
first computer Virus that appeared outside the
single computer or lab written by Richard
Skrenta.
• In 1986, The first PC Virus was a boot sector
virus dubbed ©Brain created by Farooq Alvi
Brothers in Lahore, Pakistan.

5. TYPES OF VIRUS
WHAT THEY INFECT HOW THEY INFECT
System Sector Virus Polymorphic Virus
File Virus Stealth Virus
Macro Virus Fast and Slow Infectors
Companion Virus Sparse Infectors
Cluster Virus Armored Viruses
Batch File Virus Multipartite Virus
Source Code Virus Cavity Virus
Visual Basic Worms NTFS ADS Virus

6. LOGIC OF VIRUS
• It is easy to mess-up the right program. For
example, if you remove even a single byte from
an EXE file, that EXE file won’t be usable!
• It’s a common practice to include ‘signatures’ by
virus creators.
• The main idea is to force the innocent user to run
the programs.
• Certain viruses come along with so called
‘programmer utilities’ or ‘free tools’.

7. EXAMPLE
ORKUT VIRUS / Muhaha Virus
ifwinactive ahk_classIEFrame
{
ControlGetText,ed,edit1,ahk_classIEFrame
soundplay,C:heap41a2.mp3
msgbox,262160,ORKUT IS BANNED you fool
return
}
How this works is left to the readers to analyze.........

8. VIRUS-LIKE COMPUTER PROGRAM
• Trojan Horse
A Virus-Like Program pretends to do something else is Trojan.
• Logic Bombs
A logic bomb infects a computers memory but does not
replicate.
• Malicious software
Virus-like programs that run within a web browser are called
malicious software.

9. SIGNATURE OF VIRUS
Many virus programmers add signature to their program. So
by checking the signature, we can find the name of the virus.
Most of the anti-virus packages use this logic!
Virus Signature
Einstein 0042CD217231B96E0333D2B440CD2172193BC17515B80042
Pheonix 927 E800005E81C6????BF0001B90400F3A4E8
Spanz E800005E81EE????8D94????B41ACD21C784
Necropolis 50FCAD33C2AB8BD0E2F8
Trivial-25 B44EFEC6CD21B8??3DBA??00CD2193B440CD
Trivial-46 B44EB120BA????CD21BA????B80?3DCD21%2BA0001
%4B440CD
SK CD20B80300CD1051E800005E83EE09

10. PREVENTIVE MEASURES
• Anti-Virus
• Virus Removal Using System Restore
• Operating System Re-Installation
• System Software Update

11. ANTIVIRUS
• Many users install anti-virus software that can
detect and eliminate known viruses after the
computer downloads or runs the executable.
• The first, and by far the most common
method of virus detection is using a list of
virus signature definitions.
• The second method is to use a heuristic
algorithm to find viruses based on common
behaviors.

12. EXAMPLES OF ANTIVIRUS
• Avast
• Kaspersky
• Panda
• Quick Heal
• Mc Afee
• AVG
• Norten Antivirus

13. CONCLUSION
• Computer Viruses are not just a threat to the
modern technologies but also to the security
of privacy.
• Always use Anti-Virus Software to stay
protected, and keep updating for signature
updates.
• It’s necessary to stay aware about it since we
have a computerized digital future.