security-auditor

security-auditor is a skill for Claude Code from johanthoren/jeff. It costs 74 tokens per session (976 once invoked), scanned A, original, Apache-2.0.

A security-audit workflow that examines source changes for exploitable weaknesses, using checks informed by the OWASP security guidance. It requires evidence and actionable findings instead of treating a lack of obvious matches as proof of safety.

In plain words
What is it for?
Auditing new or changed code, checking dependencies, hunting vulnerabilities, and assessing the security exposure of new features before merge.
Why use it?
It helps find security risks before code is merged and reduces the chance that the author overlooks weaknesses in their own work. Findings include the possible exploit path, risk, related weakness category, and remediation.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the jeff plugin — 4 skills, 10 agents, 1 hook shipped together

Good fit Auditing new or changed code, checking dependencies, hunting vulnerabilities, and assessing the security exposure of new features before merge.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/johanthoren/jeff/security-auditor
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.

Any agent
npx skills add johanthoren/jeff --skill security-auditor
Clone the repo
git clone --depth 1 https://github.com/johanthoren/jeff

Made for: Claude Code.

Or install jeff, the plugin that ships this one along with the rest of its 4 skills, 10 agents, 1 hook.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for security-auditor

README.md
[![agentmods](https://agentmods.dev/badge/skills/johanthoren/jeff/security-auditor/github.svg)](https://agentmods.dev/skills/johanthoren/jeff/security-auditor)
Your own site
<a href="https://agentmods.dev/skills/johanthoren/jeff/security-auditor"><img src="https://agentmods.dev/badge/skills/johanthoren/jeff/security-auditor/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for security-auditor

Your own site · 80×15
<a href="https://agentmods.dev/skills/johanthoren/jeff/security-auditor"><img src="https://agentmods.dev/badge/skills/johanthoren/jeff/security-auditor.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 976 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00074 $0.00976
Opus 5.5 $0.00030 $0.00390
Sonnet 5.5 $0.00015 $0.00195
Haiku 4.5 $0.00007 $0.00098

Measured 1mo ago against content hash 173108b39517, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

security-auditor 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 1mo ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/review_security.py, scripts/review-security.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/security-auditor/SKILL.md · 94 lines

How it starts

The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Security Auditor

Adversarial security-audit skill for the jeff pipeline.

Use this skill when you need an adversarial review that tries to break assumptions and surface exploitable weaknesses.

Load Order

For code work, load these first:

  1. code-standards
  2. language-specific skills, if present
  3. testing (when modifying checks)

Then load security-auditor.

Adversarial Posture (Anti-Shirk Contract)

  • Assume vulnerabilities exist until disproven by evidence.
  • Treat missing evidence as a risk signal, not a clean bill of health.
  • Never return PASS without full coverage ledger output.
  • Do not stop at regex hits: confirm exploit path context when possible.
  • Keep findings actionable with CWE mapping, exploit risk, and concrete remediation.
  • The implementer must never be the auditor. Whoever wrote or changed the code under review cannot sign off on its security; delegate the audit to an independent agent and never self-assess inline.

Deterministic Entry Point

The audit runner is scripts/review-security.sh, bundled in this skill's own directory. When this skill loads, its absolute location is given to you as the skill's base directory (the Base directory for this skill: … line in the skill preamble). Run the script by that absolute path, keeping your working directory in the target repo so the scan resolves the code under review from the cwd:

"<base-directory>/scripts/review-security.sh" [scope] [flags]

Do not filesystem-search for the script; resolve it from the announced base directory.

Default Checks

  • Hardcoded secrets and key material
  • Injection sinks (SQL, shell/command, path traversal)
  • Insecure deserialization
  • Weak crypto/hash usage
  • Dangerous dynamic execution (eval, exec, deserialization gadgets)
  • TLS verification disabled / insecure transport
  • XSS-prone patterns
  • Sensitive data logging
  • Dependency audit attempts (when manifest + tool exist)

Expected Output

security_audit_result:
  scope: "<resolved-scope>"
  files_scanned: <n>
  dropped_targets: [<explicitly supplied dropped target>, ...]
  findings:
    total: <n>
    critical: <n>
    high: <n>
    medium: <n>
    low: <n>
  coverage:
    categories: <n>
    uncovered: <n>
    audit_tool_failures: <n>
  recommendation: "PASS|REVIEW|BLOCK|EMPTY-SCAN"
  report_path: "scratchpads/security-audit-<timestamp>.md"

Read the full file on GitHub · 94 lines

Files

What ships with it

4 files 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. 1mo ago First seen · 94 lines · 74 tokens per session scan A 173108b39517

Subscribe to this mod's changes

security-auditor is a skill published in the GitHub repository johanthoren/jeff (6 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 74 tokens to every session and 976 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-08-31.

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