| name | phase-4-trust-boundaries |
| description | Phase 4 Trust Boundary Analysis guide. Use when defining trust zones, crossing points, and security boundaries between system components. |
Phase 4: Trust Boundary Analysis
Objective
Identify where trust levels change in the system. Every crossing point is a potential attack surface that needs security controls.
Concepts
- Trust Zone: A region where components share the same trust level
- Crossing Point: Where data flows between zones (requires authentication/authorization)
- Trust Boundary: The security perimeter with specific controls
Tools Reference
add_trust_zone(name, trust_level, description)
| Parameter | Values |
|---|
| trust_level | Untrusted, Low, Medium, High, Full |
add_component_to_zone(zone_id, component_id)
Assign a component to exactly one trust zone.
add_crossing_point(source_zone_id, destination_zone_id, authentication_method, authorization_method, description)
| Parameter | Values |
|---|
| authentication_method | Password, Multi-factor, Certificate, Token, Biometric, API Key, IAM Role, OAuth, None, Other |
| authorization_method | Role-based, Attribute-based, Discretionary, Mandatory, Policy-based, Rule-based, None, Other |
add_conn_to_crossing(crossing_point_id, connection_id)
Map existing connections to crossing points.
add_trust_boundary(name, type, crossing_point_ids, controls, description)
| Parameter | Values |
|---|
| type | Network, Process, Physical, Container, Virtual Machine, Account, Other |
| crossing_point_ids | List of crossing point IDs |
| controls | List of security control names (strings) |
Other Phase 4 Tools
list_trust_zones(), list_crossing_points(), list_trust_boundaries()
get_trust_boundary_detection_plan() -- AI-powered boundary detection
get_trust_boundary_analysis_plan() -- Security analysis guidance
Common Trust Zone Patterns
Web Application
| Zone | Trust Level | Components |
|---|
| Internet | Untrusted | End users, external APIs |
| DMZ | Low | Load balancer, CDN, WAF |
| Application | Medium | App servers, API services |
| Data | High | Databases, caches, queues |
| Admin | Full | Admin consoles, CI/CD |
Microservices
| Zone | Trust Level | Components |
|---|
| Public | Untrusted | API Gateway, public endpoints |
| Service Mesh | Medium | Internal microservices |
| Data Layer | High | Databases, object stores |
| Secrets | Full | KMS, secret managers |
Workflow
- Call
get_phase_4_guidance()
- Call
get_trust_boundary_detection_plan() for AI-guided detection
- Create trust zones based on security domains
- Assign components to zones with
add_component_to_zone()
- Define crossing points where data flows between zones
- Map connections to crossing points with
add_conn_to_crossing()
- Create trust boundaries with security controls
Completion Criteria
Common Pitfalls
- Putting everything in one trust zone
- Missing the boundary between internal services and external APIs
- Not specifying authentication/authorization at crossing points
- Forgetting admin/management plane boundaries