This document discusses different types of malicious programs including viruses, worms, Trojan horses, logic bombs, spyware, and adware. Viruses replicate by inserting copies of themselves into other programs or files. Worms replicate across network connections without needing host programs. Trojan horses appear useful but contain hidden malicious code. Logic bombs trigger when specific conditions occur. Spyware collects user information without consent. Adware automatically displays advertisements. The document provides examples of different malware types and advises users to only install trusted software and keep anti-virus software updated.

1. Malicious Code
Presented by:
Niki Patel
Hiralkumar Bhimani
Khyati Rajput
UVPCE, Ahmedabad
Guide: Prof. Ketan Savarkar

2. Contents
• Malicious Program
• Viruses
• Worms
• Trojan
• Logic Bombs
• Spywares
• Adwares

3. Malicious Program
• Malicious programs refers to a broad
category of programs that can cause
damage or undesirable effects to computer
networks.
• The other words for this is Malware
(Malicious Software), Badware, Rouge
Program (a form of internet fraud using
internet)
• Besides malicious programs there are
non-malicious programs as well.

4. Malicious program cont…
• Malicious program is not a new concept, it
was officially defined by Cohen in 1984,
but the behaviour of the viruses was first
observed in 1970.
• The damages caused because of
malicious code are:
Potential damage can include modifying.
Destroying or stealing data.

5. Gaining or allowing unauthorised access to
a system
Executing functions that a user never
intended.

6. Malicious Programs

7. Viruses:
• Viruses: A hidden self-replicating
section of computer software,
usually malicious code that
propagates by infecting (i.e.
inserting a copy into becoming a
part of) another program or
system memory.
The viruses can damage your
hardware, software or files and
replicate themselves.

8. Categories of Viruses
1. Boot sector virus :
• infect boot sector of systems.
• become resident.
• activate while booting machine
2. File virus :
• infects program files.
• activates when program is run.

9. Types of Viruses
• Can classify on basis of how they
attack
• Parasitic virus
• Memory-resident virus
• Boot sector virus
• Stealth
• Polymorphic virus
• Macro virus

10. Transient Virus is active only when its host
program is active.
Resident virus establishes itself in the computer’s
memory & can remain active without its host.
Macro Virus attached to some data file
Email Virus spread using email with attachment
containing a macro virus

11. Properties of Viruses
 Virus program should be hard to detect by
anti-virus software.
 Viruses should be hard to destroy or deactivate.
 Spread infection widely.
 Should be easy to create.
 Be able to re-infect.
 Should be machine / platform independent, so
that it can spread on different hosts.

12. Example: Melissa virus

13. Worms:
• Worms: Reproducing programs that run
independently and travel across network
connections.
• “Famous” worms are:
- Morris Internet Worm(1988)
- Code Red : had triggered time for Denial of
Service attacks.
- Code Red 2 : had backdoor installed to allow
remote control.
- Nimba : use multiple infection i.e.email,share,
web clients, etc.

14. Pikachu Worm: A K-12 Nightmare

15. This dialog box appears
after the
PIKACHUPOKEMON.EXE
file has been activated. Worm:
• Accesses Outlook Address Book
• Embeds code to delete Windows
and Windows Subfolders upon
Restart.
• +: Does ask for permission to
delete files with a “Y” command.

16. Virus v/s. Worms:
• Viruses require interaction whereas
worms act on there own.
• Viruses has to relay on users
transferring to infect files / programs
while worms can use a network to
replicate itself .
• Speed of worms is more
than viruses.

17. Trojan Horse:
• Trojan Horse:
– A Trojan horse is a program in
which malicious or harmful code is
present in such a way that it can
get a control over the system & use
to do its chosen form of damage.
─Trojans are not viruses since they do
not replicate, but Trojan horse
programs can be just as destructive.

18. Continued…
• Trojan Horses appear to be useful or
interesting to an unsuspecting user, but
are actually harmful.
• A Trojan horse can be attached to any
useful software by a cracker & can be
spread by tricking users into believing that
it is a useful program.

19. Damages caused by Trojans
• Erasing or overwriting data on a computer.
• Corrupting files.
• Installing a backdoor on a computer.
• Spreading other malware, such as viruses,
hence they are also known as “dropper”.
• Logging keystrokes to steal information
such as passwords & credit card numbers
(known as key loggers).

20. Attack of Trojan Horse
• Trojan horse attacks any system in the
following manner.

21. Situation of user after attack

22. Logic Bomb:
• Logic Bomb: A logic bomb is a
type of Trojan Horse that executes
when specific conditions occur.
– Triggers for logic bombs can include
change in a file, by a particular series of
keystrokes, or at a specific time or date.
– Suppose a programmer may hide a
piece of code that starts deleting files.

23. Spyware
• A spyware is a computer
software which is installed
automatically when you surf
internet or when you install
free software.
• Spyware is known to
change computer settings.

24. • Spyware collects various types of
information like:
Internet surfing habits.
Visited sites.
Interfere in installing additional software.
Redirect web browser activity.

25. Spyware is a legal program…..
• Here it is in the form of virus alerts.

26. Adware
• Adware is any software package which
automatically plays, displays or downloads
advertisements to a computer after the
software is installed on it or while the
application is being used.
• It’s a legal program.
• Well known adware program is
“123 Messenger”

27. 123 Messenger….
• Is in the form of popups & unexplained
advertising programs in your computer.

28. • Advertising companies
hope to generate
money from customers
who receive the popups
or unexplained programs
on their computers

29. How to detect that your computer has a
spyware or adware??
Continuous popups.
Persistent change
in your homepage.
Slower computer
processing, takes
the computer longer
to process or startup.

30. Software Security
• Only install necessary and trusted
software.
• Beware of *free* games, screen savers,
and graphics.
• Keep a hard copy of the copyright
release for all “free” products!
• Run and UPDATE anti-virus software!!

31. Thank you….