CAF – B4.a Secure by Design

Security Built Into System Design

• Network and information systems should be designed with security built in from the outset.
• Security architecture decisions should consider how threats could impact essential services, following the principles defined in the organisation’s Application and Network Security Policy.
• Structured Security Design Principles should be applied whenever systems are planned or modified.

Security Zones and Network Boundaries

• The environment should be partitioned into security zones, ensuring systems that support essential functions operate in tightly controlled, highly trusted segments.

• Clear network boundaries should be defined and managed to minimise attack surface.

• Data flows between components should remain simple, predictable and easy to monitor.

Designing for Recoverability

• Systems supporting essential functions should be designed for recoverability to allow critical services to be restored quickly.

• Where external or client-supplied inputs are processed, safeguards such as:

  • validation

  • transformation

  • sanitisation
    should be implemented to mitigate content-based attacks.

Automated Technologies

• If automated decision-making technologies are used, appropriate restrictions should be applied to prevent unintended actions that could compromise the security or resilience of essential systems.

Maintaining a Secure Architecture

• A secure-by-design approach helps ensure that no single vulnerability or architectural weakness can materially impact the services delivered.