Introduction to Network Systems Security Mort Anvari

8/24/20042 About the Course A grad-level seminar course focusing on basics and issues in network security First half will be lectures about elements of network security, cryptography backgrounds, and introduction to network security designs Second half will be your chance to present what you have learned from key research papers

8/24/20043 Why Should You Take This Course Security is an increasingly important issue You want to have basic knowledge about network security You can learn latest attacks and newest skills to counter those attacks You have a chance to implement the skills learned in the class

8/24/20044 Your Best Strategy Come to every lecture to learn basic security problems and skills to counter them Keep yourself exposed to articles related to network security to collect project ideas Read each assigned paper and write good summary for each paper Do not wait till last minute to prepare for exam or work on project Enjoy the fun!

8/24/20045 What Can Go Wrong… …when your computer y receive or is waiting for a message m? m Internet x y ?

8/24/20046 Message Loss Adversary A can discard m in its transit m x y A

8/24/20047 Message Interception Adversary A can get a copy of m when m passes by m x y m m A

8/24/20048 Message Modification Adversary A can arbitrarily modify the content of m to become m’ m x y m’ A

8/24/20049 Message Insertion Adversary A can arbitrarily fabricate a message m, pretending that m was sent by x x y m src: x dst: y A

8/24/ Message Replay Adversary A can replay a message m that has been sent earlier by x and received by y x y m m A

8/24/ Denial-of-Service Attack Adversary A can send huge amount of messages to y to block m from arriving at y x y m ……………… ????? A

8/24/ Type of Attacks Passive attacks Traffic analysis Message interception Active attacks Message loss Message modification Message insertion Message replay Denial-of-Service attack

8/24/ Network Security Services Confidentiality Integrity Authentication Anti-replay … Availability Access control Non-repudiation Anonymity

8/24/ Confidentiality Keep message known only to the receiver and secret to anyone else Counter message interception

8/24/ Integrity When receiver receives message m, receiver can verify m is intact after sent by sender Counter message modification

8/24/ Authentication When receiver receives message m, receiver can verify m is indeed sent by the sender recorded in m Counter message insertion

8/24/ Anti-replay When receiver receives message m, receiver can verify m is not a message that was sent and received before Counter message replay

8/24/ Availability Property of a system or a resource being accessible and usable upon demand by an authorized entity Counter denial-of-service attack

8/24/ Access Control Mechanism to enforce access rights to resources and data Users can access resources and data to which they have access rights Users cannot access resources and data to which they don’t have access rights

8/24/ Non-repudiation When receiver receives message m, receiver gets proof that sender of m ever sent m Receiver of m can show proof to third- party so that sender of m cannot repudiate

8/24/ Anonymity Identity of sender is hidden from receiver When receiver receives message m, receiver has no clue about sender of m

8/24/ Network Security Is Great… Protect messages from interception in their transit Detect and discard messages that are modified, inserted, or replayed Disallow unauthorized access to local system resource and sensitive data

8/24/ …But Hard To Achieve Many layers in network architecture Many different media of network connection Adversary’s location hard to determine New attacks keep emerging Cryptographic overhead

8/24/ Next Class Formal specification and verification of network protocols Network security tools to counter the effects of adversary actions