What it means
Mapping data flows across those boundaries shows where validation, authentication, authorization, encryption, monitoring, and failure handling are needed.
Why it matters
Many vulnerabilities occur at interfaces where one component trusts input, identity, or state that another component does not protect as expected.
Practical focus
- Map users, services, devices, stores, and external dependencies
- Label data sensitivity and identity context at each flow
- Identify transitions between administrative or security domains
- Revisit the map when integrations or deployment models change
Common mistakes
- Drawing only network zones
- Assuming internal traffic is trusted
- Ignoring management and recovery paths
- Documenting flows without recording validation and authorization decisions
Certification relevance
This subject appears in or supports the following certification bodies of knowledge: