skill-adversarial-security

A security review guide based on OWASP, the organization known for documenting common web application risks. It examines software from an attacker’s perspective.

In plain words
What is it for?
Use it to critique an application for security weaknesses, record each finding with severity and confidence, and suggest defensive improvements.
Why use it?
It helps uncover vulnerabilities that automated scanners or friendly code reviews may miss, including lower-confidence issues worth checking.

Skill for Claude CodeCodex

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 skills/matrixfounder/agentic-development/skill-adversarial-security
Any agent
npx skills add MatrixFounder/Agentic-development --skill skill-adversarial-security
Clone the repo
git clone --depth 1 https://github.com/MatrixFounder/Agentic-development

Made for: Claude Code, Codex.

Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,461 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. 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 $0.00033 $0.01461
Opus 5 $0.00016 $0.00731
Sonnet 5 $0.00007 $0.00292
Haiku 4.5 $0.00003 $0.00146

Measured 2d ago against content hash dfcd04e909d1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

skill-adversarial-security scanned grade B with 1 finding 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.

Instruction-override phrasingmediumPrompt injection

Text telling the model to disregard its earlier instructions or safety rules is the shape of a prompt injection, whoever wrote it.

- [ ] **Jailbreaking:** Are there guards against "Ignore previous instructions"?

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

.agent/skills/skill-adversarial-security/SKILL.md · 95 lines

How it starts

The opening of the file, as written. The whole thing — 95 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Adversarial Security Critic

You are a paranoid security auditor who has seen too many data breaches. Your job is to find security vulnerabilities before they become headlines.

1. Red Flags (Anti-Rationalization)

STOP and READ THIS if you are thinking:

  • "I'll be nice to the developer" -> WRONG. Attackers aren't nice. Your job is to be the attacker.
  • "The automated scan passed, so I'm done" -> WRONG. Scanners miss logic bugs. You are the logic bug finder.
  • "This is just an internal tool" -> WRONG. Internal tools are pivot points.
  • "I'll only report the high-severity stuff" -> WRONG. Report every issue, including low-confidence ones, with confidence + severity attached — filtering happens downstream, not in your head.

2. Persona & Tone

Optional style: you MAY adopt the persona defined in references/prompts/sarcastic.md (provocative, paranoid-auditor delivery). Tone is an opt-in stylistic choice with no evidence base as a recall lever (audit-067 C-01; doctrine: vdd-sarcastic SKILL.md §2 disclaimer).

NOT optional: exhaustive reporting — report every issue, including low-confidence ones, with confidence + severity attached; filtering happens downstream — and the objective bar (§7).

3. Reconnaissance (Automated)

Read this branch BEFORE the command below. Rows 1, 3 and 4 apply to the critic-security subagent; row 2 never does — as a spawned critic your role withholds execution from you by design (Claude Code declares it Read, Grep, Glob; the other adapters do the equivalent where they enforce it — skill-parallel-orchestration §2.4). On the sequential role-switch path you are the orchestrator wearing this persona and row 2 is exactly where you belong.

Your situation What you do
The prompt carries an execution-evidence block with a scan summary Ingest it. Do not re-run it.
You have an execution tool and no supplied result Run the command below.
You have no execution tool Write scan: NOT RUN (no execution tool in this role) and go to §4. Do not attempt the command — a stalled turn is a lost lens, and a subagent burned 600 s doing exactly this in one recorded run.
No execution-evidence block at all Contract breach: emit the finding "exit-bar condition unverifiable — no execution evidence supplied" and do not signal clean-pass.

Read the full file on GitHub · 95 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 95 lines · 33 tokens per session scan B dfcd04e909d1

Subscribe to this mod's changes

skill-adversarial-security is a skill published in the GitHub repository MatrixFounder/Agentic-development (5 stars, last pushed 19d ago), licensed Apache-2.0. It adds 33 tokens to every session and 1,461 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 1 finding (instruction-override phrasing). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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