security-scan

security-scan is a skill for Claude Code from rjmurillo/ai-agents. It costs 77 tokens per session (2,647 once invoked), scanned A, original, MIT.

A focused scanner for common command-injection patterns in Python, PowerShell, Bash, and C# code.

In plain words
What is it for?
Use it to check for CWE-78 command injection, such as shell execution or evaluating user input.
Why use it?
It can flag dangerous ways of passing user-controlled data to commands before a pull request is submitted.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: reads .claude/ paths.

Part of the project-toolkit plugin — 125 skills, 25 commands, 33 agents, 5 hooks shipped together

Good fit Use it to check for CWE-78 command injection, such as shell execution or evaluating user input.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/rjmurillo/ai-agents/security-scan
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 rjmurillo/ai-agents --skill security-scan
Clone the repo
git clone --depth 1 https://github.com/rjmurillo/ai-agents

Made for: Claude Code.

Or install project-toolkit, the plugin that ships this one along with the rest of its 125 skills, 25 commands, 33 agents, 5 hooks.

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-scan

README.md
[![agentmods](https://agentmods.dev/badge/skills/rjmurillo/ai-agents/security-scan/github.svg)](https://agentmods.dev/skills/rjmurillo/ai-agents/security-scan)
Your own site
<a href="https://agentmods.dev/skills/rjmurillo/ai-agents/security-scan"><img src="https://agentmods.dev/badge/skills/rjmurillo/ai-agents/security-scan/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-scan

Your own site · 80×15
<a href="https://agentmods.dev/skills/rjmurillo/ai-agents/security-scan"><img src="https://agentmods.dev/badge/skills/rjmurillo/ai-agents/security-scan.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 77 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,647 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Tool Misuse · line 17
    Tool parameters are crafted to achieve unintended or unsafe behavior. Parameter abuse can bypass intended safety checks (e.g. shell=True, --force, dangerous glob patterns).
    Fix: Validate all tool parameters against an allowlist. Reject dangerous parameter values (shell=True, --force, -rf /) and use safe defaults.
How audits are shown
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 $0.00077 $0.02647
Opus 5.5 $0.00031 $0.01059
Sonnet 5.5 $0.00015 $0.00529
Haiku 4.5 $0.00008 $0.00265

Measured 17d ago against content hash e22b4355e971, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

security-scan scanned grade A 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 17d ago.

The scan reads SKILL.md. This mod also ships 4 executable files (scripts/scan_constants.py, scripts/scan_format.py, scripts/scan_patterns.py, …), 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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

This skill detects **CWE-78 (command injection)** patterns only. The regex patterns target unambiguous shapes (`subprocess.run(..., shell=True)`, `eval(user_input)`, backtick command substitution, etc.) that produce reli
.claude/skills/security-scan/SKILL.md · 298 lines

How it starts

The opening of the file, as written. The whole thing — 298 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Security Scan

Proactive vulnerability detection for command injection (CWE-78) before PR submission.

Scope

This skill detects CWE-78 (command injection) patterns only. The regex patterns target unambiguous shapes (subprocess.run(..., shell=True), eval(user_input), backtick command substitution, etc.) that produce reliable signal without taint analysis.

CWE-22 (path traversal) is delegated to CodeQL. The CodeQL workflow runs python-security-extended.qls and actions-security-extended.qls on every PR, authoritatively detecting CWE-22 across Python and GitHub Actions code (the two languages CodeQL supports for this repo per codeql-config.yml). PowerShell, Bash, and C# are NOT covered by CodeQL; for those languages, CWE-22 detection relies on code review and any future static analyzer adoption. Per the buy-vs-build framework analysis (issue #1843), maintaining a custom regex-based CWE-22 detector created false positives (PR #1841 added seven suppression annotations to silence them) without comparable coverage of real CWE-22 vectors that CodeQL catches in CI. Path-traversal checking is Context (table stakes security, not a competitive differentiator); CodeQL is the right tool for the languages it supports.

If a CWE-22 finding surfaces in CI from CodeQL, fix the underlying code or flag it to the owner. Do not add a regex-based CWE-22 check to this scanner.

Triggers

Trigger Phrase Operation
scan for vulnerabilities scan_vulnerabilities.py on staged/specified files (CWE-78 only)
check for command injection scan_vulnerabilities.py with CWE-78 focus
check for path traversal NOT handled by this scanner. CWE-22 detection is delegated to CodeQL (see the CodeQL Analysis workflow, which runs python-security-extended.qls).
pre-PR security scan scan_vulnerabilities.py on staged files
run security scan scan_vulnerabilities.py with full scan

Read the full file on GitHub · 298 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. 17d ago Changed e22b4355e971
  2. 22d ago Changed · +5 lines 284c7589be39
  3. 24d ago Changed fa3945827b44
  4. 1mo ago First seen · 293 lines · 77 tokens per session scan A 03e48076bcda

Subscribe to this mod's changes

security-scan is a skill published in the GitHub repository rjmurillo/ai-agents (48 stars, last pushed today), licensed MIT. It adds 77 tokens to every session and 2,647 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.