Computer Security Lecture: Key Concepts, Terminology, and Threats, Slides of Computer Security

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Lecture 2:

Overview (cont)

Key Security Concepts

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Confidentiality

• preserving authorized restrictions on information access and disclosure.
• including means for protecting personal privacy and proprietary information

Integrity

• guarding against improper information modification or destruction,
• including ensuring information nonrepudiation and authenticity

Availability

• ensuring timely and reliable access to and use of information

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.

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 system's

design, implementation, or operation and management that could be exploited to violate the system's security policy.

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

Countermeasures

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means used to deal with security attacks

may introduce new vulnerabilities Residual vulnerabilities may remain goal is to minimize residual level of risk to the assets

• prevent
• detect
• recover

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.

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

Scope of Computer Security

Computer and Network Assets

Security Functional Requirements

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computer security technical measures

• access control
• identification & authentication;
• system & communication protection
• system & information integrity

management controls and procedures

• awareness & training
• audit & accountability
• certification, accreditation, & security assessments
• contingency planning
• maintenance
• physical & environmental protection
• planning
• personnel security
• risk assessment
• systems & services acquisition

overlap computer security technical measures and management controls

• configuration management
• incident response
• media protection

• assuring a communication is from the source that it claims to be from
• interference by a third party masquerading as one of the two legitimate parties - Peer Entity Authentication - corroboration of the identity of a peer entity - confidence that an entity is not performing - a masquerade or - an unauthorized replay 17

Authentication Service

 Data Origin Authentication  corroboration of the source of a data  supports applications where there are no prior interactions

• protection of transmitted data from passive attacks
• Protects user data transmitted over a period of time - connection confidentiality - connectionless confidentiality - selective-field confidentiality - protects the traffic flow from analysis - traffic-flow confidentiality

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Data Confidentiality Service

• can apply to a stream of messages, a single message, or selected fields within a message
• with and without recovery
  • connectionless integrity service
    • provides protection against message modification only
  • connection-oriented integrity service - assures that messages are received as sent - no duplication, insertion modification, reordering, or replays

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Data Integrity Service