exchanet Skill: Phase 3 — Risk Matrix
Purpose
Execute Phase 3: perform STRIDE threat modeling on the primary API surface, build a technical risk catalog, and ensure all CRITICAL risks have mitigations before proceeding to implementation.
STRIDE Analysis Template
| Threat | Component | Attack vector | Severity | Mitigation |
|---|---|---|---|---|
| Spoofing | [Component] | [Attack] | HIGH/CRITICAL | [Mitigation] |
| Tampering | [Component] | [Attack] | HIGH/CRITICAL | [Mitigation] |
| Repudiation | [Component] | [Attack] | MEDIUM/HIGH | [Mitigation] |
| Info Disclosure | [Component] | [Attack] | CRITICAL | [Mitigation] |
| Denial of Service | [Component] | [Attack] | HIGH | [Mitigation] |
| Elevation of Privilege | [Component] | [Attack] | CRITICAL | [Mitigation] |
Technical Risk Catalog Template
| Risk | Probability | Impact | Score | Mitigation |
|---|---|---|---|---|
| [Technical risk] | L/M/H | CRITICAL/HIGH/MEDIUM | [Calculated] | [Mitigation strategy] |
Risk scoring: Probability × Impact = Score
- Low × Critical = HIGH
- Medium × Critical = HIGH
- High × Critical = CRITICAL
Examples from banking-walkthrough.md
STRIDE — Payment API:
- Info Disclosure (IDOR): Customer accesses another customer's transactions — CRITICAL — mitigated by strict account ownership check at repository layer (not controller — prevents bypass)
- DoS: Request flood on payment endpoint — HIGH — mitigated by rate limiting (per account + per IP) + circuit breaker
Technical Risks:
- Card network timeout mid-authorization — Medium probability × CRITICAL impact — mitigated by Saga with compensation + idempotency keys + Outbox pattern
- PostgreSQL primary failure — Low probability × CRITICAL impact — mitigated by synchronous multi-AZ replication + Patroni HA + RTO ≤30s
Gate rule
No CRITICAL risk may remain unmitigated. If a CRITICAL risk has no mitigation, it blocks Phase 4.
All HIGH risks must have at least a documented mitigation strategy (implementation can be deferred, but the strategy must exist).
Output artifact
Save as docs/risk-matrix.md or append to the main planning document.