Security Threat Modeling

Deliver an actionable AppSec-grade threat model specific to the repository, not a generic checklist. Anchor every architectural claim to evidence in the repo and keep assumptions explicit. Prioritize realistic attacker goals and concrete impacts.

Workflow

1. Scope and Extract the System Model

• Identify primary components, data stores, and external integrations from the repo
• Identify how the system runs (server, CLI, library, worker) and its entrypoints
• Separate runtime behavior from CI/build/dev tooling and from tests/examples
• Map in-scope locations and exclude out-of-scope items explicitly
• Do not claim components, flows, or controls without evidence

2. Derive Boundaries, Assets, and Entry Points

• Enumerate trust boundaries as concrete edges between components
• Note protocol, auth, encryption, validation, and rate limiting at each boundary
• List assets that drive risk: data, credentials, models, config, compute resources, audit logs
• Identify entry points: endpoints, upload surfaces, parsers, job triggers, admin tooling

3. Calibrate Attacker Capabilities

• Describe realistic attacker capabilities based on exposure and intended usage
• List assets that drive risk: credentials, PII, integrity-critical state, availability
• Explicitly note non-capabilities to avoid inflated severity

4. Enumerate Threats as Abuse Paths

• Map attacker goals to assets and boundaries
• Focus on: exfiltration, privilege escalation, integrity compromise, denial of service
• Classify each threat and tie it to impacted assets
• Keep the number of threats small but high quality

5. Prioritize with Explicit Reasoning

• Use qualitative likelihood and impact (low/medium/high) with short justifications
• Set overall priority (critical/high/medium/low) using likelihood x impact
• State which assumptions most influence the ranking

6. Validate with the User

• Summarize key assumptions that affect threat ranking or scope
• Ask 1-3 targeted questions to resolve missing context
• Pause and wait for user feedback before producing the final report

7. Recommend Mitigations

• Distinguish existing mitigations (with evidence) from recommended mitigations
• Tie mitigations to concrete locations and control types
• Prefer specific implementation hints over generic advice

8. Quality Check

• Confirm all entrypoints are covered
• Confirm each trust boundary is represented in threats
• Confirm runtime vs CI/dev separation
• Write the final Markdown to

  <repo-name>-threat-model.md

Risk Prioritization Guidance

• High: Pre-auth RCE, auth bypass, cross-tenant access, sensitive data exfiltration, key/token theft, sandbox escape
• Medium: Targeted DoS, partial data exposure, rate-limit bypass, log poisoning
• Low: Low-sensitivity info leaks, noisy DoS with easy mitigation, unlikely preconditions