threat-modeling

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name: threat-modeling description: Threat modeling skill for STRIDE analysis, attack tree construction, and security requirement extraction. Use when designing new features, reviewing architecture, conducting threat modeling sessions, creating security documentation, or training teams on security thinking. Triggers: threat model, STRIDE, attack tree, DFD, security design, threat analysis, security architecture review. allowed-tools: Read, Grep, Glob, Bash agent: threat-modeling-expert metadata: triggers: threat model, STRIDE, attack tree, security design, threat analysis, security architecture review, DFD related-skills: security-reviewer, sast-configuration, architecture-design domain: security role: architect scope: design output-format: document last-reviewed: "2026-03-15"

Iron Law: NO ARCHITECTURE REVIEW WITHOUT THREAT MODELING FIRST

Every new feature, service, or architectural change requires a threat model before implementation begins.

When to Use

• New feature or service design → STRIDE analysis + DFD
• Architecture change → full DFD analysis of affected components
• Production security incident → post-incident threat review
• Security audit preparation → staleness check on all threat models

Process

1. Load methodology — Read references/stride-methodology.md for STRIDE matrix, DFD element mapping, risk scoring, and output template
2. Load control library — Read references/threat-mitigation-mapping.md for control categories, the 16-control lookup table, and coverage scoring
3. Model the system — Identify assets, trust boundaries, DFD elements, and interactions
4. Run STRIDE — Apply per-element and per-interaction analysis using the methodology reference
5. Map mitigations — Select controls from the library; verify defense-in-depth across layers
6. Score and report — Calculate risk = impact × likelihood, document residual risks

References

File	Content	Load When
references/stride-methodology.md	STRIDE matrix, DFD mapping, risk scoring formula, output template	STRIDE analysis, DFD mapping, risk scoring
references/threat-mitigation-mapping.md	Control library (16 controls), coverage scoring, budget prioritization	Selecting security controls, budget prioritization

Error Handling

If architecture documents are missing, reconstruct system topology from the codebase using Grep/Glob. If a component lacks context for threat analysis, flag it explicitly rather than guessing.