threat-modeling

Bitwarden's Engagement Model

Bitwarden follows a 4-phase engagement model for security work. This skill primarily supports Phase 1 (engineering-owned) and assists with Phase 2-4 artifacts.

Phase 1: Initial Security Assessment (Engineering Team)

1. Check Bitwarden's Architecture Decision Records for existing decisions covering the system or components under review (see ${CLAUDE_PLUGIN_ROOT}/references/adr-alignment.md) — a threat model should align with already-accepted architecture, not silently re-derive or contradict it
2. Create data flow diagrams (Mermaid)
3. Define security requirements separate from product requirements
4. Propose security definitions (threat model + security goals)
5. Identify initial threats using STRIDE (see references/stride-framework.md)

Phase 2: AppSec Team Review (AppSec + Engineering)

• Share data flow diagrams and security definitions in advance
• Walk through system architecture collaboratively
• Validate or refine proposed security definitions
• Identify additional threats, assess risk
• Avoid assuming external mitigations exist