Network security Topic 2 overview continued

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Network security Topic 2 overview continued

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Network security Topic 2 overview continued

  1. 1. Lecture 2:Overview (cont)
  2. 2. 2 Key Security Concepts Confidentiality Integrity Availability • preserving • guarding against • ensuring timely authorized improper and reliable access restrictions on information to and use of information access modification or information and disclosure. destruction, • including means • including ensuring for protecting information personal privacy nonrepudiation and proprietary and authenticity information
  3. 3. 3 Computer Security Terminology • Adversary (threat agent) - An entity that attacks, or is a threat to, a system. • Attack - An assault on system security that derives from an intelligent threat; a deliberate attempt to evade security services and violate security policy of a system. • Countermeasure - An action, device, procedure, or technique that reduces a threat, a vulnerability, or an attack by eliminating or preventing it, by minimizing the harm it can cause, or by discovering and reporting it so that corrective action can be taken.
  4. 4. 4 Computer Security Terminology • Risk - An expectation of loss expressed as the probability that a particular threat will exploit a particular vulnerability with a particular harmful result. • Security Policy - A set of rules and practices that specify how a system or org provides security services to protect sensitive and critical system resources. • System Resource (Asset) - Data; a service provided by a system; a system capability; an item of system equipment; a facility that houses system operations and equipment.
  5. 5. 5 Computer Security Terminology • Threat - A potential for violation of security, which exists when there is a circumstance, capability, action, or event that could breach security and cause harm. • Vulnerability - Flaw or weakness in a systems design, implementation, or operation and management that could be exploited to violate the systems security policy.
  6. 6. 6 Security Concepts and Relationships
  7. 7. 7 Vulnerabilities, Threats and Attacks • vulnerabilities – leaky (loss of confidentiality) – corrupted (loss of integrity) – unavailable or very slow (loss of availability) • threats – capable of exploiting vulnerabilities – represent potential security harm • attacks (threats carried out) – passive or active attempt to alter/affect system resources – insider or outsider
  8. 8. 8 Countermeasures • prevent means used to deal • detect with security attacks • recover may introduce new vulnerabilities Residual vulnerabilities may remain goal is to minimize residual level of risk to the assets
  9. 9. 9 Threat Consequences • Unauthorized disclosure is a threat to confidentiality • Exposure: This can be deliberate or be the result of a human, hardware, or software error • Interception: unauthorized access to data • Inference: e.g., traffic analysis or use of limited access to get detailed information • Intrusion: unauthorized access to sensitive data
  10. 10. 10 Threat Consequences • Deception is a threat to either system or data integrity • Masquerade: e.g., Trojan horse; or an attempt by an unauthorized user to gain access to a system by posing as an authorized user • Falsification: altering or replacing of valid data or the introduction of false data • Repudiation: denial of sending, receiving or possessing the data.
  11. 11. 11 Threat Consequences • Disruption is a threat to availability or system integrity • Incapacitation: a result of physical destruction of or damage to system hardware • Corruption: system resources or services function in an unintended manner; unauthorized modification • Obstruction: e.g. overload the system or interfere with communications
  12. 12. Usurpationu·sur·pa·tion (ysr-pshn, -zr-)n.1. The act of usurping, especially thewrongful seizure of royal sovereignty.2. A wrongful seizure or exercise of authorityor privilege belonging to another; anencroachment: "in our own day, grossusurpations upon the liberty of private life"(John Stuart Mill).
  13. 13. 13 Threat Consequences • Usurpation is a threat to system integrity. • Misappropriation: e.g., theft of service, distributed denial of service attack • Misuse: security functions can be disabled or thwarted
  14. 14. 14 Scope of Computer Security
  15. 15. 15 Computer and Network Assets
  16. 16. 16 Passive and Active Attacks • Passive attacks attempt to learn or make use of information from the system but does not affect system resources – eavesdropping/monitoring transmissions – difficult to detect – emphasis is on prevention rather than detection – two types: • message contents • traffic analysis • Active attacks involve modification of the data stream – goal is to detect them and then recover – four categories: • masquerade • replay • modification of messages • denial of service
  17. 17. 17 Security Functional Requirements overlap computer computer security management controls security technical technical measures and procedures measures and management controls • access control • awareness & training • configuration • identification & • audit & accountability management authentication; • certification, accreditation, • incident response • system & & security assessments • media protection • contingency planning communication • maintenance protection • physical & environmental • system & information protection integrity • planning • personnel security • risk assessment • systems & services acquisition
  18. 18. Reading Assignment http://en.wikipedia.org/wiki/Cyber_Intelligence_Sharing_and_ Protection_Act
  19. 19. 19  Data Origin Authentication Authentication ● corroboration of the source of a Service data ● supports applications where there are no prior interactions • assuring a communication is • Peer Entity Authentication from the source that it claims – corroboration of the identity to be from of a peer entity – confidence that an entity is • interference by a third party not performing masquerading as one of the – a masquerade or two legitimate parties – an unauthorized replay
  20. 20. 20 Access Nonrepudiation Control Service Service  prevents either sender or • limit and control the access to receiver from denying a host systems and applications transmitted message • each entity trying to gain access must first be identified, or authenticated
  21. 21. 21 Data – connection confidentiality Confidentiality Service – connectionless confidentiality – selective-field confidentiality • protection of transmitted data from passive attacks – protects the traffic flow from analysis • Protects user data transmitted over a period – traffic-flow confidentiality of time
  22. 22. 22 • connectionless integrity service Data – provides protection against Integrity message modification only Service • connection-oriented integrity service – assures that messages are • can apply to a stream of received as sent messages, a single message, – no duplication, insertion or selected fields within a modification, reordering, or message replays • with and without recovery
  23. 23. 23 • a variety of attacks can result in the loss of or reduction in Availability availability Service – some of these attacks are amenable to authentication and encryption – some attacks require a physical action to prevent or recover from loss of • a service that protects a availability system to ensure its availability – being accessible and – depends on proper usable upon demand by management and control an authorized system of system resources entity
  24. 24. 24 Security Mechanism • Feature designed to – Prevent attackers from violating security policy – Detect attackers’ violation of security policy – Recover, continue to function correctly even if attack succeeds. • No single mechanism that will support all services – Authentication, authorization, availability, confidentiality, integrity, non-repudiation
  25. 25. 25 Security Trends
  26. 26. 26 Security Technologies
  27. 27. 27 Security Policy • formal statement of rules and practices that specify or regulate security services • factors to consider: – value of the protected assets – vulnerabilities of the system – potential threats and the likelihood of attacks • trade-offs to consider: – ease of use versus security – cost of security versus cost of failure and recovery
  28. 28. 28 Assurance and Evaluation • assurance – the degree of confidence one has that the security measures work as intended – both system design and implementation • evaluation – process of examining a system with respect to certain criteria – involves testing and formal analytic or mathematical techniques
  29. 29. 29

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