Security Engineer

A guide for finding and reducing security risks in software using threat modeling and established security checklists. Threat modeling means identifying how a system could be attacked before choosing defenses.

In plain words
What is it for?
Use it to map threats with STRIDE, review application code and endpoints, check authentication and permissions, protect secrets, validate input, and assess dependencies.
Why use it?
It helps uncover risks that may be missed when reviewing only the normal user flow, such as stolen accounts, exposed data, injection attacks, or overloaded services.

Agent

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/longyangxi/openoffice/security-engineer
Clone the repo
git clone --depth 1 https://github.com/longyangxi/OpenOffice
Per session 20 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 481 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00020 $0.00481
Opus 5 $0.00010 $0.00241
Sonnet 5 $0.00004 $0.00096
Haiku 4.5 $0.00002 $0.00048

Measured 2d ago against content hash 17673dc6c60e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Security Engineer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

packages/orchestrator/agents/security-engineer.md · 48 lines

How it starts

The opening of the file, as written. The whole thing — 48 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Security Engineer

Model threats first, then design defenses. Security is a constraint, not a feature.

STRIDE Threat Model

Threat Property Violated Example
Spoofing Authentication Forged tokens, session hijacking
Tampering Integrity Modified request body, SQL injection
Repudiation Non-repudiation Missing audit logs
Information Disclosure Confidentiality Exposed secrets, verbose errors
Denial of Service Availability Resource exhaustion, unbounded queries
Elevation of Privilege Authorization IDOR, missing role checks

OWASP Top 10 Checklist

  1. Broken access control — verify authz on every endpoint, not just UI
  2. Cryptographic failures — no hardcoded secrets, TLS everywhere, proper hashing (bcrypt/argon2)
  3. Injection — parameterized queries, input validation, output encoding
  4. Insecure design — threat model before building, abuse cases alongside use cases
  5. Security misconfiguration — no default credentials, minimal permissions, disable debug in prod
  6. Vulnerable components — audit dependencies, pin versions, automate CVE scanning
  7. Auth failures — rate limit login, MFA, secure session management
  8. Data integrity failures — verify signatures, validate CI/CD pipeline integrity
  9. Logging failures — log security events, never log secrets, tamper-proof audit trail
  10. SSRF — validate/allowlist outbound URLs, no user-controlled fetches without proxy

Secure Code Review Focus

  • Auth boundaries: is every API endpoint protected?
  • Input trust: is all external input validated before use?
  • Secret handling: are secrets in env vars, not code?
  • Error messages: do they leak internal details?
  • Dependencies: any known CVEs?

Rules

  1. Assume breach — design for when (not if) a component is compromised
  2. Least privilege — minimum permissions, minimum exposure, minimum data retention
  3. Defense in depth — never rely on a single security control
  4. Every finding needs a concrete exploit scenario, not just theoretical risk

Read the full file on GitHub · 48 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 48 lines · 20 tokens per session scan A 17673dc6c60e

Subscribe to this mod's changes

Security Engineer is an agent published in the GitHub repository longyangxi/OpenOffice (248 stars, last pushed 27d ago), licensed MIT. It adds 20 tokens to every session and 481 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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