Security Architecture Document

A Security Architecture Document (SAD) is a comprehensive design document of the security system. It describes the security vision, controls, and implementation details of the security architecture, serving as a blueprint for the security team and wider development organization.

A good SAD functions as a central reference point for security design decisions. It can also be shared with stakeholders (e.g., management, auditors, compliance teams) to clearly convey the security approach. It is important that the SAD is a living document that is updated as the threat landscape evolves, so that security decisions and changes are documented and traceable.

Starting Points

• NIST Risk Management Framework - System Security Plan
• OWASP Software Assurance Maturity Model (SAMM)
• ISO 27001 Information Security Documentation

Key Points

• Presence of a structured SAD in which all core components of the security architecture are elaborated (threat model, security controls, defense-in-depth strategy, authentication/authorization mechanisms, encryption standards, etc.).
• The SAD is actively maintained throughout the project: changes in security requirements or threat landscape are reflected in updates to the document (version control should be applied to security documentation).
• The document is clear and complete enough that an outsider (e.g., a new security team member or auditor) gains understanding of the security vision and implementation. Any gaps or ambiguities in the SAD are recognized and addressed by the security specialist.
• The document includes traceability between security requirements, identified threats, and implemented controls to demonstrate comprehensive security coverage.