CS475 Network and Information Security

Transcription

1 CS475 Network and Information Security Lecture 1 Introduction Elias Athanasopoulos eliasathan@cs.ucy.ac.cy

2 What is this course all about? Understand the fundamental concepts of security in software, systems, and the network Broad range of security topics No very deep dives Hands-on experience 2

3 Why computer security is important? 3

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8 It s a mess 8

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10 It can only get worse 10

11 Why it so complicated? Systems have different building layers Hardware, Software, Network, Protocols Heavy interraction and interconnection Internet of Things People 11

12 Our topics Applied Crypto Software Security Network Security Web Security Mobile Security Anonymity and Privacy Concepts of different topics interract with each other! 12

13 Resources No single textbook to cover everything, the topic is rapidly changing I will provide many resources on a per-lecture basis (papers, articles, software, etc.) Some suggested (free) material: Handbook of Applied Cryptography, Security Engineering, Some suggested (non free) material: Introduction to Computer Security, by Michael T. Goodrich and Roberto Tamassia (ISBN-13: , ISBN-10: ) 13

14 Let s go! 14

15 What is computer security? Computer security, also known as cyber security or IT security, is the protection of computer systems from the theft or damage to their hardware, software or information, as well as from disruption or misdirection of the services they provide. Gasser, Morrie (1988). Building a Secure Computer System (PDF). Van Nostrand Reinhold. p. 3. ISBN , E458/building-secure-systems.pdf) 15

16 What is computer security? A property that affects systems Hardware, software, network Degrading this property leads to bad things Theft, damage, disruption, misdirection Degrading this property is deliberate An attacker degrades the security of a system on purpose Suggested read 16

17 Example 1 An application needs to transmit sensitive data Submitting a password Sending a personal message Just reading sensitive data is enough to break security Leak the password, or the personal message 17

18 Example 2 An application needs to transmit sensitive data Submit the details of a financial transaction Submit the casting of a vote Modifying the sensitive data can break the security Modify the financial transaction, or the vote 18

19 Security Requirements From Example 1 and 2, we can see that security can imply several different subproperties Different applications have different security requirements, which can be grouped Confidentiality, Integrity, Availability, Authentication, Non-repudiation, Accounting, Privacy Suggested reference: 19

20 Confidentiality The property that information is not made available or disclosed to unauthorized individuals, entities, or processes (i.e., to any unauthorized system entity) 20

21 Integrity Data integrity: The property that data has not been changed, destroyed, or lost in an unauthorized or accidental manner System integrity: Assures that a system performs its intended function in an unimpaired manner, free from deliberate or inadvertent unauthorized manipulation of the system 21

22 Availability The property of a system or a system resource being accessible and usable upon demand by an authorized system entity, according to performance specifications for the system; i.e., a system is available if it provides services according to the system design whenever users request them 22

23 CIA Confidentiality The property that information is not made available or disclosed to unauthorized individuals, entities, or processes (i.e., to any unauthorized system entity) Integrity Data integrity: The property that data has not been changed, destroyed, or lost in an unauthorized or accidental manner System integrity: Assures that a system performs its intended function in an unimpaired manner, free from deliberate or inadvertent unauthorized manipulation of the system Availability The property of a system or a system resource being accessible and usable upon demand by an authorized system entity, according to performance specifications for the system; i.e., a system is available if it provides services according to the system design whenever users request them 23

24 An Example Confidentiality: Bad guys cannot see messages Availability: The system is operational Communication System/Service Integrity: Bad guys cannot change messages 24

25 Example 1 Confidentiality An application needs to transmit sensitive data Submitting a password Sending a personal message Just reading sensitive data is enough to break security Leak the password, or the personal message 25

26 Example 2 Integrity An application needs to transmit sensitive data Submit the details of a financial transaction Submit the casting of a vote Modifying the sensitive data can break the security Modify the financial transaction, or the vote 26

27 Additional Requirements Non-repudiation One party of a transaction cannot deny having received a transaction nor can the other party deny having sent a transaction 27

28 Additional Requirements Access Control Identification I claim I am John Smith (i.e., by submitting a username) Authentication System verifies that I am John Smith (e.g., through password) Authorization As John Smith I am authorized to perform a particular action (i.e., post a message) 28

29 Privacy The right of an entity (normally a person), acting in its own behalf, to determine the degree to which it will interact with its environment, including the degree to which the entity is willing to share information about itself with others 29

30 Security Context Threat Model List the attacker s capabilities List the attacker s goal Often, list the defenses that are in place Often, list the affected risks of the target system using security requirements (CIA) Security isn t a scalar. It doesn t make sense to ask Is device X secure? without a context: secure against whom and in what environment? 30

31 Example Threat Model Passive Man-in-the-Middle An attacker that can passively monitor network packets exchanged between two parties Attacker wants to reveal the conversation Conversation is encrypted using the cryptosystem X Confidentiality can be affected if attacker can break cryptosystem X Integrity, and Availability cannot be affected 31

32 Course Logistics 32

33 Ethics The course has many offensive parts Using the offensive part in the wild is strictly forbidden Our goal is to understand attacks for building better defenses 33

34 Logistics 45% Final 25% Midterm 30% Assignments 20% Programming assignments (4 in total and in C/C++) 10% Quiz Success All assignments have been submitted Final written exam is at least 4,5 Final score is at least 5 34