Security Models and Threats

Work in progress. This note is still being written and incomplete.

2 min read Last updated Sun Jul 05 2026 05:11:45 GMT+0000 (Coordinated Universal Time)

Access Control

The 3 basic actions of a person on an item of data: viewing (confidentiality), modifying (integrity), using (availability). These are the basic modes of access computer security seeks to preserve.

Access control is the basic model or paradigm of security. Several other models support specific computer security objectives:

  • BLP model
    Data confidentiality and sharing, by David Bell and Leonard La Padula.
  • Biba model
    Data integrity, by Kenneth Biba.
  • Chinese Wall model
    Preventing conflict of interests in shared information systems.

Types of Threats

Threats to computer security exist for data, systems, and services.

  • Non-human origin
    Hardware, software, network, or power failure.
  • Human origin, benign intent
    Human error in initiating a wrong action or giving wrong input.
  • Human origin, malicious intent
    Autonomous attacks initiated by humans, either random (worms, viruses, malicious web pages or scripts, phishing emails) or directed (spear phishing, impersonation).

Advanced Persistent Threat

An advanced persistent threat (APT) is a directed attack designed to snare a high value target, e.g. stealing a company CEO’s email password, or cause extremely high damage, e.g. destroying a uranium enrichment plant.

APT attacks are executed by coordinated human actions rather than through program code alone. Attackers are skilled, motivated, organized, and well funded.

  • Advanced
    Attackers have a full spectrum of intelligence-gathering techniques at their disposal.
  • Persistent
    Attackers have specific objectives, rather than opportunistically seeking information for financial or other gain.
  • Threat
    Attackers constitute a high-level threat because they have both capability and intent for severe damage or loss.
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