This document discusses computer viruses and antivirus software. It defines a computer virus as a type of malicious software program that replicates itself and spreads from one computer to another. It explains that viruses are created by hackers, criminals, and others seeking profit or revenge. The document outlines several major types of viruses like worms, file infectors, macro viruses, and Trojan horses. It emphasizes the importance of using antivirus software to prevent viruses from infecting systems and causing data loss or other harm. The conclusion is that computers should always be protected with up-to-date antivirus security before transferring or opening any files.

1. SUBMITTED TO –
VINEET KATHURIA
SUBMITTED BY –
SHUBHAM VERMA
97 ITT BATCH
REG. NO. –
CRO0564909

2. WHAT IS COMPUTER VIRUS?
• Computer viruses are a type of software program that, like a
biological virus, reproduces and spreads itself
• Some virus may display only a message on the screen, others may
slow down the Pc
• They can also erase files or even format your floppy or hard disk
and crash the system.

3. WHO CREATES/WRITES VIRUSES ?
INFO ATTACKERS PROFIT EARNER
 VIRUS / ANTIVIRUS
MARKET
 PSYCHO CASES
 FOR FUN
 TO TAKE REVENG
 RELEASE ANGER

4. TYPE OF VIRUSES
• There are about millions of viruses present & daily 6 to 7 new viruses
are found
• The following are some types of viruses:
Boot sector Virus Program/ File Infector
Trojan Horses Worms, Macro Virus
Polymorphic Virus Companion Virus
FAT Virus Logic Bombs
Spyware Adware
Multipartite virus Stealth virus etc.

5. MAJOR TYPES OF VIRUSES
VIRUS
Worms
Program/
File
Infector
Macro
Viruses
Trojan
Horses
Boot
Sector
Virus

6. BOOT SECTOR VIRUS
•The boot Sector virus affects the
booting process of the infected
computer system, thus causing slow
start up and shut down process

7. PROGRAM / FILE INFECTOR VIRUS
• Becomes active when the
program file carrying the virus is
opened.
• A file-infecting virus overwrites
code or inserts infected code into
a executable file
• usually with below extensions
.BIN .COM
.EXE .OVL
.DRV

8. WORMS
• A computer worm is a self-replicating computer program.
• It uses a network to send copies of itself to other nodes
(computer terminals on the network) and it may do so without
any user intervention.
• Unlike a virus, it does not need to attach itself to an existing
program. Worms always harm the network (if only by
consuming bandwidth), whereas viruses always infect or
corrupt files on a targeted computer.

9. Worm Propagation
Leverage: Network Connectivity

10. MACRO VIRUS
• These type of virus
infects word , excel,
PowerPoint, access
and other data files.
Once infected
repairing of these files
is very much difficult.

11. TROJAN HORSES
•A Trojan horse is a program that unlike a
virus contains or installs a malicious program
(sometimes called the payload or 'trojan').
• The term is derived from the classical myth
of the Trojan Horse.
• Trojan horses may appear to be useful or
interesting programs to an unsuspecting user,
but are actually harmful when executed.
• The famous usage in hacking.

12. TROJAN

13. SOME EXAMPLES OF VIRUSES
Boot Sector Virus
Form
Disk Killer
Michelangelo
Stone virus
 Program / File Infector Virus
 Cascade
 Sunday
 Worms
 ILOVEYOU
 Code Red
 Melissa
 Storm Worm
 Macro Virus
 DMV
 Nuclear
 Word Concept
 Melissa Worm.
 Trojan Horses
 Vundo
 Zeus Trojan

14. THE FUNCTIONAL LOGIC OF A VIRUS
 Search for a file to infect.
 Open the file to see if it is infected.
 If infected, search for another file.
 Else, infect the file.
 Return control to the host program.

15. VIRUS
V
Virus – Needs a host

16. Virus Propagation
Leverage : User Connectivity

17. CAUSES AND EFFECTS OF COMPUTER
VIRUSES
• Computer viruses spread by attaching themselves to the other
computer program files(usually .exe, .com, .bat, .dll, )
• A computer virus may be hidden or protected from the users
eye
• These viruses spread through infected files in Floppy, Cd, Usb
pen drive & internet
• Computer viruses can infect the program and it may lead to loss of
important data
• These viruses are transfers to our data through any floppy or cd
• If any infected file is copy in your system then it will infect the other
files and function too

18. CURE OF COMPUTER VIRUSES

19. PREVENTION & CURE OF
COMPUTER VIRUSES
• Since virus can cause extensive effect to your important
files,possible steps must be take to prevent attack on your pc
• If you use floppy disk to boot your pc then write protect it
• Make backups of your impotent files in floppy or cd and keep
it in a safe place you will need it later
• Install an Antivirus software
• Regularly update the program
• Open email attachment files only if you are expecting the
attached files, or the sender is known and has confirmed
sending the file
• Try to avoid downloading and installing software from the
Internet
• Install only registered copies of software on the system

20. ANTI-VIRUS

21. WHAT IS AN ANTI-VIRUS?
• Anti-virus is a software (computer program)
that scans files or your computer's memory
for certain patterns that may indicate an
infection.
• The patterns it looks for are based on the
signatures, or fingerprints, of known viruses.
computer programs intended to Identify
and Eliminate Computer Viruses.

22. SOME ANTI-VIRUSES SOFTWARE

23. CONCLUSION
• I think we should not use the pc without any antivirus security
as it may cause damage to our important data
• Do not copy or transfer any data or file without scanning the
disk.

25. ANY QUESTIONS ?