DEPENDABLE AND SECURE COMPUTING
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reliability, availability, safety, integrity, maintainability, faults, errors, failures
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DEPENDABLE AND SECURE COMPUTING
- 1. Seminar: Advanced Topics in Software and Systems Engineering Presenter: Sabbir Ahmmed
- 2. Motivation Basic Concepts and Taxonomy of Dependable and Secure Computing
- 3. Motivation
- 4. Motivation
- 5. Motivation ● Main definitions relating to dependability ○ reliability ○ availability ○ safety ○ integrity ○ maintainability ● additional definitions ○ threats to dependability and security ○ e.g faults, errors, failures ● means for their achievement ○ fault prevention, fault tolerance ○ fault removal, fault forecasting etc
- 6. Introduction "Basic Concepts and Taxonomy of Dependable and Secure Computing" by A. Avizienis, J.C. Laprie, B. Randell, C. Landwehr ● 2525 citations ● 360 citations ● 315 citations
- 7. Introduction This paper aims to give precise definitions of ● dependability and security ● computing and communications systems ● focus on concepts
- 8. Introduction This paper does not address the ● measures of dependability and security ● documenting state-of-the-art ● implementations issues ● confidentiality
- 9. Basic Concepts ● Basic set of definitions ● Entire range of computing and communications systems ○ individual logic gates ○ networks of computers ○ computer based systems
- 10. Basic Concepts ● System function ● Behaviour ○ described by a sequence of states ○ total states ■ computation ■ communication ■ stored information ■ interconnection ■ physical connection ● Structure ● Service
- 11. Basic Concepts Threats to dependability and Security ● Failures ○ also known as service failure ○ a transition from correct service to incorrect service ○ service outage and service restoration ● Errors ○ when at least one external state of the system deviates from correct service state ● Faults ○ hypothesized cause of an error ○ could be internal or external ○ could be active or dormant
- 12. Basic Concepts [Mordechai Ben-Ari, Weizmann Institute of Science] (1999) The bug that destroyed a rocket
- 13. Basic Concepts Software Hall of Shame
- 14. Basic Concepts Software Growth Picture Credit: Dr. Werner J.A. Dahm, Director, Security & Defense Systems Initiative, Arizona State University
- 15. Basic Concepts ● Degraded mode/partial failures ○ slow service ○ limited service ○ emergency service
- 16. Basic Concepts Dependability ○ ability to deliver a service that can justifiably be trusted ○ ability to avoid service failures ○ encompasses the following attributes ■ availability ■ reliability ■ safety ■ integrity ■ maintainability
- 17. Basic Concepts Security ○ is a composite of the attributes ■ confidentiality ■ integrity ■ availability
- 18. Basic Concepts Means to attain dependability and security ● Fault prevention ● Fault tolerance ● Fault removal ● Fault forecasting
- 19. Threats to dependability System life cycle ● Development phase ○ physical world ○ human developers ○ development tools ○ production and test facilities ● Use phase ○ users ○ administrators ○ the infrastructure ○ intruders ○ ....
- 20. Threats to dependability Forms of maintenance
- 21. Threats to dependability A Taxonomy of Faults ○ development fault ○ physical faults ○ interaction faults
- 22. Faults The elementary fault classes 31 likely combinations/256 possible combinations ● Natural Faults ○ internal ○ external ● Human-made Faults ○ omission faults ○ commission faults
- 23. Faults
- 24. Faults
- 25. Faults Classification of Human-made faults ● Non- malicious Faults ○ accidental ○ incompetence
- 26. Faults ● Malicious faults ○ malicious logic faults ■ logic bomb ■ Trojan horse ■ trapdoor ■ virus ■ worm ■ zombie ○ intrusion attempts
- 27. Failures Service failure modes Failures modes With respect to failure domain
- 28. Failures Development failures and principal causes AAS example ($ 1.5 billion) ● Complete development failure ○ budget failure ○ schedule failure ● Partial development failure ○ overruns (example F-35) ○ downgrading (example F-35) Dependability and security failures AAS example (outage limit)
- 29. Errors ● Detected errors ● Latent errors ● Multiple related errors ● Single errors
- 31. Faults Single vs Multiple Independent vs Related
- 32. Chain of threats
- 33. The way forward
- 34. Means to attain dependability ● Fault Prevention ● Fault Tolerance ● Fault Removal ○ during development ■ verification ■ diagnosis ■ correction ○ during use
- 39. Conclusion