Cryptography and Network Security Tanzim Malicious Software and Virus

2. Topics
Virus
Malicious software

3. Malicious software
Malicious Software (Malware) :
Malicious software, commonly known as malware, is any software that
brings harm to a computer system. Malware can be in the form of worms,
spyware, trojan, adware, viruses and rootkits, etc.

4. Terminology of malicious software
Virus :
Attaches itself to a program and propagates copies if itself to other
programs .
Worm :
Program that propagates copies of itself to other computers .
Logic bomb :
Triggers actions when action occurs .
Trojan horse :
Program that contains unexpected additional functionality .
Exploits :
Code specific to a single vulnerability or set of vulnerabilities .
Downloaders :
Program that installs other items on a machine that is under attack .
Usually a downloader is sent in an e-mail .

5. Terminology of malicious software
Auto-rooter :
Malicious hacker tools used to break into new machines remotely .
Flooders :
Used to attack networked computer system with a large volume of traffic
to carry out a denial-of-service (DoS) attack .
Keyloggers :
Captures keystrokes on a compromised system .
Rootkit :
Set of hackers tools used after attacker ha broken into a computer system
and gained root-level access .
Zombie :
Program activated on an infected machine that is activated to launch
attacks on other machines .

6. Virus
Virus :
Self-replicating code attaches itself to another program and executes
secretly when the host program is executed .
A virus goes through following four phases --
1. Dormant phase
2. Propagation phase
3. Triggering phase
4. Execution phase

7. Phases of Virus

8. Classifications of Virus
There are various types of virus --
1. Parasitic virus
2. Memory resident virus
3. Boot sector virus
4. Stealth virus
5. Polymorphic virus
6. Metamorphic virus

9. Classifications of Virus
Parasitic virus :
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 types of virus lives in memory after its execution . It inserts itself
as a part of operating system or application and can manipulate any file
that is executed , copied or moved .
Boot sector virus :
This type of virus infects the boot records and spread through a
system when a system is booted from disk containing virus .

10. Classifications of Virus
Stealth virus :
It is the virus who hide the modification it has made in the file or
boot record .
Polymorphic virus :
It produces fully operational copies of itself , in an attempts to avoid
signature detection .
Metamorphic virus :
Rewrite itself completely with every new host , may change their
behavior and appearance .

11. Conclusion
So--
It(virus) is harmful to our system and we should always use antivirus
software to protect our system . We can use Linux operating system to
avoid viruses and worms because Linus does not support viruses .

12. THANK YOU…..