1. Data & Network Security
Mrs. Iqra Shahid
Lecturer
Department of Computer Science

2. Instructor MS Computer Science from UOL (Sargodha Campus).
BS Computer Science from UET Lahore.
Have 3 research papers published.
Pre-coding Techniques (OFDMA)
Distributed Denial of Service (Network Security)
Multi-Level Queue and Real time Scheduling (Operating System)

3. Students Introduction

4. Introduction to Course

5. Teaching Procedure Lectures Discussion Assignments Surprise Quizzes
Midterm
Presentation
Final Exam

6. Marks Distribution Class Participation 05% Assignments 05%
Surprise Quizzes 10%
Midterm 30%
Presentation 10%
Final Exam 40%

7. Prerequisites
Data Communication & Networks
Computer Networks

8. Textbook
Cryptography and Network Security, William Stallings, 5th Edition, Pearson Education, 2011
Cryptography & Network Security, Behrouz A. Frouzen
Security in Computing, Charles P. Pfleeger, Fourth Edition, Pearson Education, 2011.
Online readings

9. Objectives of the lecture
To define Security
To define three security goals
To define security attacks that threaten security goals
To define security services and how they are related to the three security goals
To define security mechanisms to provide security services
To introduce two techniques, cryptography an steganography, to implement security mechanisms.
1.#

10. Introduction
The art of war teaches us to rely not on the likelihood of the enemy's not coming, but on our own readiness to receive him; not on the chance of his not attacking, but rather on the fact that we have made our position unassailable.
—The Art of War, Sun Tzu

11. Background
Information Security requirements have changed in recent times.
Traditionally provided by physical and administrative mechanisms.
Computer use requires automated tools to protect files and other stored information.
Use of networks and communications links requires measures to protect data during transmission.

12. Computer Security
The protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity, availability and confidentiality of information system resources (includes hardware, software, firmware, information/data, and telecommunications). [NIST 1995]

13. Definitions
Computer Security - generic name for the collection of tools designed to protect data and to thwart hackers.
Network Security - measures to protect data during their transmission.
Internet Security - measures to protect data during their transmission over a collection of interconnected networks.

14. Aim of Course Our focus is on Data & Network Security
Which consists of measures to prevent, detect, deter and correct security violations that involve the transmission & storage of information.

15. Security Trends

16. Security Goals This section defines three security goals.
Confidentiality
Integrity
Availability

17. Confidentiality
Confidentiality is probably the most common aspect of information security.
We need to protect our confidential information.
An organization needs to guard against those malicious actions that endanger the confidentiality of its information.

18. Integrity Information needs to be changed constantly.
Integrity means that changes need to be done only by authorized entities and through authorized mechanisms.

19. Availability
The information created and stored by an organization needs to be available to authorized entities.
Information needs to be constantly changed, which means it must be accessible to authorized entities.

20. Examples of Security Requirements
Confidentiality – student grades
integrity – patient information
Availability – authentication service

21. Levels Of Impact 3 levels of impact from a security breach Low
Moderate
High

22. OSI Security Architecture
ITU-T X.800 “Security Architecture for OSI”
Defines a systematic way of defining and providing security requirements.
For us it provides a useful, if abstract, overview of concepts we will study.

23. Aspects of Security Consider 3 aspects of information security:
Security Attack
Security Mechanism
Security Service

24. Security Attack
Any action that compromises the security of information owned by an organization.
Information security is about how to prevent attacks, or failing that, to detect attacks on information-based systems.
Often threat & attack used to mean same thing.

25. Security Attack
The three goals of security - confidentiality, integrity, and availability can be threatened by security attacks.
Attacks Threatening Confidentiality
Attacks Threatening Integrity
Attacks Threatening Availability
Passive versus Active Attacks

26. Taxonomy of Attacks

27. Attacks Threading Confidentiality
Snooping refers to unauthorized access to or interception of data.
Traffic analysis refers to obtaining some other type of information by monitoring online traffic.

28. Attacks Threatening Integrity
Modification means that the attacker intercepts the message and changes it.
Masquerading or spoofing happens when the attacker impersonates somebody else.
Replaying means the attacker obtains a copy of a message sent by a user and later tries to replay it.
Repudiation means that sender of the message might later deny that she has sent the message; the receiver of the message might later deny that he has received the message.

29. Attacks Threatening Availability
Denial of service (DoS) is a very common attack. It may slow down or totally interrupt the service of a system.

30. Passive Attacks (i) Release of Message Contents

31. Passive Attacks (ii) Traffic Analysis

32. Passive Attacks (Cont…)
Passive attacks do not affect system resources
Eavesdropping, monitoring
Two types of passive attacks
Release of message contents
Traffic analysis
Passive attacks are very difficult to detect
Message transmission apparently normal
No alteration of the data
Emphasis on prevention rather than detection
By means of encryption

33. Active Attacks (i) Masquerade

34. Active Attacks (ii) Replay

35. Active Attacks (iii) Modification of Messages

36. Active Attacks (iv) Denial of Service

37. Active Attacks (Cont…)
Active attacks try to alter system resources or affect their operation
Modification of data, or creation of false data
Four categories
Masquerade
Replay
Modification of messages
Denial of service: preventing normal use
A specific target or entire network
Difficult to prevent
The goal is to detect and recover

38. Passive versus Active Attacks