This document discusses viruses and worms, including their types, lifecycles, advantages, and disadvantages. It defines viruses as code that attaches itself to other programs to damage computer systems or networks, while worms are a type of virus that can replicate itself but not attach to other programs. The document outlines different types of viruses and phases in their lifecycles. It compares viruses to worms and lists disadvantages like deleting files or causing system malfunctions. The conclusion recommends using antivirus software and Linux to protect against viruses and worms.

1. Presented by:
Kartik N. Kalpande..!

2. Agenda
 Introduction
 Types of Viruses
 Phases of Virus
 Difference between Virus & Worms
 Advantages
 Disadvantages
 Conclusion

3. Introduction
 Virus:-
A virus is a code or program that attaches itself to
another code or program which causes damage to the computer
system or to the network
It can replicate them. all computer viruses are manmade.
Any simple viruses can make a copy of itself over and over again.
Any simple viruses can be dangerous because it will
quickly use all available memory space and bring the system to a
halt.
Whereas, dangerous viruses are capable of transmitting
itself across networks and can be able to avoid security system.

4. Worms
 A worm is a special type of virus that can replicate itself
and use memory but can not attach itself to other
program
 Virus and worms will be the most common problem
that an organization faces
 Highly organized criminal groups want use the
technology used in worm propagation and virus, but
their use are normally interested in accomplishing is
limited.

5. Type of Viruses
 Parasitic viruses:-
It attaches itself to executable code and replicates itself. When the
infected code is executed it will find other executable code or program to
infect.
 Memory resident virus:-
This type of virus lives in memory after its execution. It inserts themselves
as a part of operating system or application and can manipulate any file
that is executed, copied or moved.
 Non-resident virus:-
This type of virus executes itself and terminated or destroyed after
specific time .
 Overwriting virus:-
This types of virus overwrite the code with its own code.

6.  Boot sector virus:-
This type of virus infects the boot record and spread through a
system when a system is booted from disk containing virus.
 Stealth virus:- it is the virus who hide the modification it has
made in the file or boot record.
 Macro virus:-
This viruses are not executable.It affects microsoft word like
documents they can spread through email.
 Companion virus:-
This is the virus which create a new program instead of modifying
an existing file

7.  Email viruses:-
Virus get executed when email attachment is open by
recipient. virus send itself to everyone on the mailing
list of sender.
 Polymorphic virus:-
It produces fully operational copies of itself,in an
attempts to avoid signature detection.

8. Phases of viruses(Life cycle of
Virus)
 Dormant phase:-
This virus is idle and eventually activated by some events.
 Propagation phase:-
The virus places and identical copy of itself into other
programs or into certain system areas on the disk
 Triggering phase:-
The virus is activated to perform the function for which it
was intended.
 Execution phase:-
In this phase the virus performs its actual operation.

9. Disadvantages
 It delete files in system.
 When a computer system is infected due to virus then it is
difficult to recover.
 Virus causes malfunctioning of a computer system
 It automatically attach to the executable file and replicate itself.
 It occupies disk space.

10. Difference between Virus and Worm
 Virus does not replicate itself whereas worm replicate
itself
 Virus is destructive in nature whereas worm is non
destructive
 Virus can infect other file whereas worm does not
infect other file but it occupies memory space by
replication
 Aim of virus is to infect the code or program stored on
computer system whereas the aim worm is to mac
computer and network unusable.

11. Conclusion
 It is harmful to our system so we should always use
antivirus software to protect our system
 We can use Linux operating system to avoid viruses and
worms because Linux does not support viruses

12. Thank You!!!