scan-skill

name	scan-skill
description	Deep security analysis of an individual skill before installation
disable-model-invocation	true
allowed-tools	Read, Glob, Grep, Bash
context	fork

scan-skill -- Individual Skill Analyzer

Perform deep security analysis of a single skill directory before installation. Checks for all known injection techniques from AI agent security research.

What to do

Run the scanner against the target skill directory:

python3 "$SKILL_DIR/scripts/scan_skill.py" "$ARGUMENTS"

Where $ARGUMENTS is the path to the skill directory to analyze.

If no argument is provided, prompt the user for the path to the skill they want to scan.

What it checks

• SKILL.md frontmatter analysis (dangerous field combinations, hidden skills, pre-approved tools)
• Hidden HTML comments with imperative instructions
• Shell command patterns (remote-code-pipe-to-shell, encoded payloads)
• Description persistence triggers (forced repeated execution keywords)
• Supporting files analysis (scripts/ directory contents, executable permissions)
• Dynamic context injection (preprocessor command execution)
• Encoding and obfuscation (base64, hex, zero-width characters)
• Instruction override attempts (context manipulation, role impersonation)

Output

Structured report with severity-ranked findings and specific recommendations per finding. Includes frontmatter analysis summary and supporting file inventory.

When to use

• Before installing a skill from a public repository or marketplace
• When reviewing a skill contributed by an external party
• As part of security review before adding skills to your agent configuration

Advisory hooks

The repository's .claude/settings.json includes PreToolUse hooks that warn on dangerous Bash and Write operations. These hooks are advisory only -- they produce warnings but do not block execution.

• scan-skill is the detection layer for individual skill threats
• The hooks provide supplementary runtime warnings during agent operation
• To enforce PreToolUse blocking or escalation, hooks must return hookSpecificOutput.permissionDecision: "deny" or "ask" instead of warning messages