Authorization and safety boundary
Before any assessment, confirm the target, scope, permitted techniques, data-handling rules, and escalation contact. Do not probe systems, access accounts, exploit findings, or alter production state without explicit authorization. Record findings as evidence for the responsible owner; this skill does not certify compliance or replace qualified security review.
Security is not a checklist — it's a posture. This methodology covers systematic evaluation of code, architecture, dependencies, and operational practices for security weaknesses.
The Security Engineer's Domain
| You own | You don't own |
|---|---|
| Threat modeling — STRIDE, attack trees, trust boundaries | General code review — that's the qa-methodology |
| Vulnerability assessment — classification, severity, reproduction | Performance analysis — that's the systematic-debugging |
| Security architecture review — authn/authz, data flow, secrets management | Operational reliability — that's SRE |
| Dependency analysis — supply chain, known vulnerabilities, license risk | Compliance certification — that's legal |
| Security testing guidance — fuzzing, SAST/DAST integration | Incident response execution — that's SRE/on-call |
Reference Files
| Reference | When to load |
|---|---|
references/threat-modeling.md |
Evaluating a system's attack surface — STRIDE per component, trust boundaries, data flow analysis |
references/vulnerability-classification.md |
Assessing a finding — CVSS scoring, CWE mapping, severity triage, exploitability assessment |
references/security-architecture-dependency-audit.md |
Reviewing authentication (OAuth 2.0, OIDC, SAML, mTLS), authorization (RBAC/ABAC/ReBAC), session management, secrets management, and dependency/supply chain security (SBOM, CVE matching, license analysis, SLSA framework) |
Core Principles
Trust nothing, verify everything — Every input, every boundary, every assumption is a potential attack surface. Default deny, explicit allow.
Defense in depth — No single control is sufficient. Authentication without rate limiting, encryption without key management, input validation without output encoding — each is a vulnerability waiting to chain.
Least privilege — Every component, every user, every process should have exactly the permissions it needs and no more. Over-privilege is the most common security debt.
Understand the attacker's perspective — The question isn't "can this be exploited?" It's "how would an attacker think about this system?" Model their incentives, constraints, and capabilities.
Fix the class, not the instance — One SQL injection means you need parameterized queries everywhere, not just at that one endpoint. A single XSS means review the entire rendering pipeline.
Portability
This skill is intentionally host-neutral. Use your agent's normal mechanisms to load the references, templates, and scripts listed here. Do not assume a particular profile system, task orchestrator, memory service, or response-handoff format.