Security Threat Model

Purpose

Use this skill before implementing or approving security-sensitive changes. It complements auth-security and server-security by mapping assets, attackers, trust boundaries, and concrete controls.

Scope First

Identify:

1. Assets: credentials, tokens, user data, tenant data, money movement, admin actions.
2. Actors: anonymous user, authenticated user, tenant admin, internal operator, compromised dependency.
3. Trust boundaries: browser/server, service/service, tenant/tenant, CI/runtime, third-party callbacks.
4. Entry points: API routes, CLI commands, jobs, webhooks, uploads, config files.
5. Existing controls: validation, authz, rate limits, audit logs, secret storage.

Threat Checklist

Check at least:

• Spoofing: can an identity, tenant, callback, or service be forged?
• Tampering: can payloads, configs, migrations, artifacts, or logs be altered?
• Repudiation: is there an audit trail for sensitive actions?
• Information disclosure: can secrets, PII, logs, or tenant data leak?
• Denial of service: can expensive paths be amplified?
• Elevation of privilege: can user or service permissions expand?
• Supply chain: can dependencies, scripts, CI, or generated files introduce risk?

Required Controls

Every finding needs one of:

• preventive control in production code,
• detective control with alerting,
• compensating manual control with owner and expiry,
• explicit accepted risk with rationale.

Do not accept "warn and continue" for authz, secrets, tenant isolation, injection, or payment/security-critical failures.

Output Shape

scope:
assets:
trust_boundaries:
entry_points:
threats:
required_controls:
tests_or_probes:
residual_risks:
review_gate:

For implementation work, include exact files and verification commands that prove the controls are active.