1. GL
BAL
Institute of Information Technology

2. A Presentation on
Computer Virus
Group Name:- G3
Group Members :-
Rohitash kumar
Rahul Baghla
Ravikant Verma

3. Contents
:-
 What is a virus
 Types of virus
 Indications of Virus Attack
 Creating a virus

Protecting from virus

Remove some common virus

Conclusion

4. What is a virus?
• A computer virus is a computer program that can
copy itself and infect a computer without permission or
knowledge of the user.
• A virus can only spread from one computer to another
when its host is taken to the uninfected computer, for
instance by a user sending it over a network or the
Internet, or by carrying it on a removable medium such
as a floppy disk, CD, or USB drive.

5. Types of Viruses
 Trojan Horse
 Memory Resident Virus
 Worms
 Root kit Virus
 Boot sector Virus
 Polymorphic Virus
 Macro Virus
 Logic Bombs

6. What are Trojan Horses ?
• A Trojan horse is a computer program that is hiding a
virus or other potentially damaging program. A
Trojan horse can be a program that purports to do one
action when, in fact, it is performing a malicious
action on your computer. Trojan horses can be
included in software that you download for free or as
attachments in email messages.

7. What is a Worm?
• 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 almost always cause harm to the
network, if only by consuming bandwidth, whereas viruses
almost always corrupt or modify files on a targeted
computer.

8. Boot Sector Virus :-
A boot sector virus infects boot
sector of computers. During system boot, boot sector virus is
loaded into main memory and destroys data stored in hard
disk.
Macro Virus :-
Macro viruses are viruses that use another
application's macro programming language to distribute themselves. They
infect documents such as MS Word or MS Excel and are typically spread
to other similar documents.

9. Memory Resident Virus :-
Memory Resident Viruses reside in a computers
volatile memory (RAM). They are initiated from a virus which runs on the
computer and they stay in memory after it's initiating program closes.
Root kit Virus :A root kit virus is an undetectable virus which
attempts to allow someone to gain control of a computer system. The term
root kit comes from the Linux administrator root user. These viruses are
usually installed by Trojans and are normally disguised as operating
system files.

10. Polymorphic Virus :Polymorphic viruses contain complex
instructions that enable them to mutate into new and different viruses.
This makes it impossible for anti-viruses to find them using string or
signature searches (because they are different in each encryption). The
virus then goes on creating a large number of copies.
Logic Bombs :Logic bombs are often attached to a working
program but do not replicate. They are only executed when a certain
predefined condition is met. Their objective is to destroy data on the
computer once certain conditions have been met.

11. Indications of Virus Attack
 Computer runs slower then usual
 Computer no longer boots up
 Screen sometimes flicker
 PC speaker beeps periodically
 System crashes for no reason
 Files/directories sometimes disappear

12. How To Create a Virus
As we know, Virus is nothing it
is just a program which are created for
malicious purpose. If it occurs in a
system & user is unaware of from it
then it can destroy or damage our
system.

13. Continued..
Open Notepad and write the following code
@Echo off
Start virus.bat
virus.bat
save it as .bat and run it.
It will hang our computer & we have to shut
down the computer forcibly...

14. Protection from Virus
 Install reliable anti-virus software
 Update our anti-virus software regularly
 Don't automatically open attachments
 Scan all incoming email attachments
 Delete chain emails and junk email
 Be careful when downloading files from the Internet

15. Continued…
 Always scan new files for viruses before we use them
 Backup our files on a regular basis
 If our computer is on a network, make sure we have
security steps in place to prevent unauthorized users
putting files on our computer
 Take care using USB flash cards, CDs, zip and floppy
disks

16. Examples of risky file types :• The following file types should be treated with
suspicion and be confirmed with the sender before
being opened:
– .exe
– .bat
– .vbs

17. Remove Some Common Viruses
• We can remove some of the common viruses
without help of any antivirus Program.
• e.g.- New Folder.exe
• Autorun.inf ( from PDs etc)

18. New Folder.exe
• It looks just like an folder but
actually it is a .exe file.
• Try to deleting the file.
• It will delete if you haven’t
executed it, if you’re unable
to delete it.
• Go to Task manager ( by
pressing ctrl+shift+esc )

19. Continued …
 Go to Process Tab and try
finding that the process for
the exe file and end the
process.
 Then Go to the same folder
containing the exe file and
delete it.
 Then Open Search and try
finding the .exe files of same
size and delete them all.

20. Removal of Autorun.inf
• Open Run dialog Box. Type in “CMD” press
ENTER.

21. Continued …
• The Command Prompt will Open Now. In Command
prompt go to the drive containing Autorun.inf
• Now Type In “ attrib –h –s –a” and press enter.

22. Continued …
• This will remove drives attributes for all Hidden,
System files.
• Now Type “ Del autorun.inf” and press ENTER.
• The Virus has been Successfully Removed.

23. “It is good to be aware of
viruses rather than being
sorry…..”

24. Thank You !!
Any Queries ??