July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-1 Chapter 1: Introduction Components of computer security Threats Policies and mechanisms The role of trust Assurance Operational Issues Human Issues

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-2 Basic Components (Goals) Confidentiality –Keeping data and resources hidden Integrity –Data integrity (integrity) –Origin integrity (authentication) Availability –Enabling access to data and resources

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-3 Additional Goals Authentication –Correctly identifying the source Non-repudiation –Being able to prove the source of an utterance to a third party

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-4 Terms Exposure –Possible form of loss Vulnerability –Possible mechanism by which loss can occur Threat –Circumstance or event that could cause loss Attack –Attempt to exploit vulnerability Control –Mechanism to mitigate exposures

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-5 Overall Process Identify and Classify Assets –What are we protecting? How are they important? Identify Exposures and Threats –What would be bad? How could it happen? Identify Vulnerabilities and Threat Sources –Who or what could cause loss, and how? Determine Policies and Controls –What should be allowed and what disallowed? –How will the policies be enforced Implement and Monitor –Deploy controls and use them, gain experience to update p.r.n.

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-6 Chapter 1: Introduction Components of computer security Threats Policies and mechanisms The role of trust Assurance Operational Issues Human Issues

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-7 Classes of Threats Disclosure –Snooping Deception –Modification, spoofing, repudiation of origin, denial of receipt Disruption –Modification Usurpation –Modification, spoofing, delay, denial of service

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-8 Chapter 1: Introduction Components of computer security Threats Policies and mechanisms The role of trust Assurance Operational Issues Human Issues

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-9 Policies and Mechanisms Policy says what is, and is not, allowed –This defines “security” for the site/system/etc. Mechanisms enforce policies Composition of policies –If policies conflict, discrepancies may create security vulnerabilities

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-10 “Goals” of Security (Control Approaches) Prevention –Prevent attackers from violating security policy Detection –Detect attackers’ violation of security policy Recovery –Stop attack, assess and repair damage –Continue to function correctly even if attack succeeds

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-11 Chapter 1: Introduction Components of computer security Threats Policies and mechanisms The role of trust Assurance Operational Issues Human Issues

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-12 Trust and Assumptions Underlie all aspects of security Policies –Unambiguously partition system states –Correctly capture security requirements Mechanisms –Assumed to enforce policy –Support mechanisms work correctly

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-13 Types of Mechanisms secure precise broad set of reachable statesset of secure states

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-14 Chapter 1: Introduction Components of computer security Threats Policies and mechanisms The role of trust Assurance Operational Issues Human Issues

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-15 Assurance Confidence that system will perform in a predictable way Generally, intent is that it will perform correctly!

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-16 Achieving Assurance Specification –Requirements analysis –Statement of desired functionality Design –How system will meet specification Implementation –Programs/systems that carry out design

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-17 Chapter 1: Introduction Components of computer security Threats Policies and mechanisms The role of trust Assurance Operational Issues Human Issues

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-18 Operational Issues Cost-Benefit Analysis –Is it cheaper to prevent or recover? Risk Analysis –Should we protect something? –How much should we protect this thing? Laws and Customs –Are desired security measures illegal? –Will people do them?

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-19 Chapter 1: Introduction Components of computer security Threats Policies and mechanisms The role of trust Assurance Operational Issues Human Issues

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-20 Human Issues Organizational Problems –Power and responsibility –Financial benefits People problems –Outsiders and insiders –Social engineering

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-21 Tying Together Threats Policy Specification Design Implementation Operation

July 1, 2004Computer Security: Art and Science © Matt Bishop Slide #1-22 Key Points Policy defines security, and mechanisms enforce security –Confidentiality –Integrity –Availability Trust and knowing assumptions Importance of assurance The human factor