skill-scanner-skill

name	skill-scanner-skill
description	Scan SKILL.md files for security vulnerabilities and malicious patterns. Use when: (1) reviewing skills before installation, (2) auditing existing skills, (3) checking for prompt injection, data exfiltration, tool poisoning, or obfuscation, (4) user asks to "scan skill", "check skill security", or "find malicious skills".

Skill Scanner

Detect security threats in SKILL.md files.

Threat Categories

Category	Priority	Examples
Prompt Injection	P0	ignore previous instructions, you are now, <system>
Tool Poisoning	P1	$(rm -rf /), sudo access, system tags in descriptions
Data Exfiltration	P1	~/.ssh/, process.env, API keys, tokens
Obfuscation	P1	Zero-width chars, RTL override, Base64, homoglyphs

Usage

Scan a skill file:

python3 scripts/scan.py <path-to-SKILL.md>

Scan multiple files:

python3 scripts/scan.py skill1/SKILL.md skill2/SKILL.md

Output formats:

python3 scripts/scan.py file.md --format console  # default
python3 scripts/scan.py file.md --format json
python3 scripts/scan.py file.md --format sarif    # GitHub Advanced Security

Exit Codes

• 0: No critical or high severity issues
• 1: Critical or high severity issues found

Workflow

1. Run scan on target SKILL.md files
2. Review findings by severity (critical > high > medium > low)
3. Report results to user with file locations and matched patterns
4. Recommend action based on severity (reject if critical/high found)