How do I install the Skill Guard skill?

Run npx skillmds@latest add modbender/skill-guard in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Skill Guard safe to use?

This skill has not completed SkillMD's automated safety review yet. Independent scanners report: SkillSpector: FAIL, Skill Scanner: WARNING. Capability flags: executes scripts, makes network calls. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Skill Guard?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Skill Guard free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Skill Guard?

modbender (@modbender) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Skill Guard by modbender — Agent Skill

Name: Skill Guard
Rating: 4.2 (5 reviews)
Author: modbender

Skill Guard

Scan ClawHub skills for security vulnerabilities BEFORE installing. Use when installing new skills from ClawHub to detect prompt injections, malware payloads, hardcoded secrets, and other threats. Wraps clawhub install with mcp-scan pre-flight checks.

modbender Updated Sep 9, 2026 12 repo stars

File contents

skill-guard

The only pre-install security gate for ClawHub skills.

Why skill-guard?

	VirusTotal (ClawHub built-in)	skillscanner (Gen Digital)	skill-guard
When it runs	After publish (server-side)	On-demand lookup	Before install (client-side)
What it checks	Malware signatures	Their database	Actual skill content
Prompt injections	❌	❌	✅
Data exfiltration URLs	❌	❌	✅
Hidden instructions	❌	❌	✅
AI-specific threats	❌	❌	✅
Install blocking	❌	❌	✅

VirusTotal catches known malware binaries — but won't flag .

skillscanner checks if Gen Digital has reviewed it — but can't scan new or updated skills.

skill-guard uses mcp-scan (Invariant Labs, acquired by Snyk) to analyze what's actually in the skill, catches AI-specific threats, and blocks install if issues are found.

The Problem

Skills can contain:

🎭 Prompt injections — hidden "ignore previous instructions" attacks
💀 Malware payloads — dangerous commands disguised in natural language
🔑 Hardcoded secrets — API keys, tokens in plain text
📤 Data exfiltration — URLs that leak your conversations, memory, files
⛓️ Toxic flows — instructions that chain into harmful actions

One bad skill = compromised agent. Your agent trusts skills implicitly.

The Solution

# Instead of: clawhub install some-skill
./scripts/safe-install.sh some-skill

skill-guard:

Downloads to staging (/tmp/) — never touches your real skills folder
Scans with mcp-scan — Invariant/Snyk's security scanner for AI agents
Blocks or installs — clean skills get installed, threats get quarantined

What It Catches

Real example — skill-guard flagged this malicious skill:

● [E004]: Prompt injection detected (high risk)
● [E006]: Malicious code pattern detected  
● [W007]: Insecure credential handling
● [W008]: Machine state compromise attempt
● [W011]: Third-party content exposure

VirusTotal: 0/76 engines. mcp-scan caught what antivirus missed.

Usage

# Secure install (recommended)
./scripts/safe-install.sh <skill-slug>

# With version
./scripts/safe-install.sh <skill-slug> --version 1.2.3

# Force overwrite
./scripts/safe-install.sh <skill-slug> --force

Exit Codes

Code	Meaning	Action
`0`	Clean	Skill installed ✓
`1`	Error	Check dependencies/network
`2`	Threats found	Skill quarantined in `/tmp/`, review before deciding

When Threats Are Found

Skill stays in /tmp/skill-guard-staging/skills/<slug>/ (quarantined). You can:

Review — read the scan output, inspect the files
Install anyway — mv /tmp/skill-guard-staging/skills/<slug> ~/.openclaw/workspace/skills/
Discard — rm -rf /tmp/skill-guard-staging/

Requirements

clawhub CLI — npm i -g clawhub
uv — curl -LsSf https://astral.sh/uv/install.sh | sh

Why This Matters

Your agent has access to your files, messages, maybe your whole machine. One malicious skill can:

Read your secrets and send them elsewhere
Modify your agent's behavior permanently
Use your identity to spread to other systems

Trust, but verify. Scan before you install.

---name: skill-guarddescription: Scan ClawHub skills for security vulnerabilities BEFORE installing. Use when installing new skills from ClawHub to detect prompt injections, malware payloads, hardcoded secrets, and other threats. Wraps clawhub install with mcp-scan pre-flight checks.--- # skill-guard **The only pre-install security gate for ClawHub skills.** ## Why skill-guard? | | **VirusTotal** (ClawHub built-in) | **skillscanner** (Gen Digital) | **skill-guard** | |---|---|---|---| | **When it runs** | After publish (server-side) | On-demand lookup | **Before install (client-side)** | | **What it checks** | Malware signatures | Their database | **Actual skill content** | | **Prompt injections** | ❌ | ❌ | ✅ | | **Data exfiltration URLs** | ❌ | ❌ | ✅ | | **Hidden instructions** | ❌ | ❌ | ✅ | | **AI-specific threats** | ❌ | ❌ | ✅ | | **Install blocking** | ❌ | ❌ | ✅ | **VirusTotal** catches known malware binaries — but won't flag ``. **skillscanner** checks if Gen Digital has reviewed it — but can't scan new or updated skills. **skill-guard** uses [mcp-scan](https://github.com/invariantlabs-ai/mcp-scan) (Invariant Labs, acquired by Snyk) to analyze what's actually in the skill, catches AI-specific threats, and blocks install if issues are found. ## The Problem Skills can contain: - 🎭 **Prompt injections** — hidden "ignore previous instructions" attacks - 💀 **Malware payloads** — dangerous commands disguised in natural language - 🔑 **Hardcoded secrets** — API keys, tokens in plain text - 📤 **Data exfiltration** — URLs that leak your conversations, memory, files - ⛓️ **Toxic flows** — instructions that chain into harmful actions **One bad skill = compromised agent.** Your agent trusts skills implicitly. ## The Solution ```bash # Instead of: clawhub install some-skill ./scripts/safe-install.sh some-skill ``` skill-guard: 1. **Downloads to staging** (`/tmp/`) — never touches your real skills folder 2. **Scans with mcp-scan** — Invariant/Snyk's security scanner for AI agents 3. **Blocks or installs** — clean skills get installed, threats get quarantined ## What It Catches Real example — skill-guard flagged this malicious skill: ``` ● [E004]: Prompt injection detected (high risk) ● [E006]: Malicious code pattern detected ● [W007]: Insecure credential handling ● [W008]: Machine state compromise attempt ● [W011]: Third-party content exposure ``` VirusTotal: 0/76 engines. **mcp-scan caught what antivirus missed.** ## Usage ```bash # Secure install (recommended) ./scripts/safe-install.sh <skill-slug> # With version ./scripts/safe-install.sh <skill-slug> --version 1.2.3 # Force overwrite ./scripts/safe-install.sh <skill-slug> --force ``` ## Exit Codes | Code | Meaning | Action | |------|---------|--------| | `0` | Clean | Skill installed ✓ | | `1` | Error | Check dependencies/network | | `2` | Threats found | Skill quarantined in `/tmp/`, review before deciding | ## When Threats Are Found Skill stays in `/tmp/skill-guard-staging/skills/<slug>/` (quarantined). You can: 1. **Review** — read the scan output, inspect the files 2. **Install anyway** — `mv /tmp/skill-guard-staging/skills/<slug> ~/.openclaw/workspace/skills/` 3. **Discard** — `rm -rf /tmp/skill-guard-staging/` ## Requirements - `clawhub` CLI — `npm i -g clawhub` - `uv` — `curl -LsSf https://astral.sh/uv/install.sh | sh` ## Why This Matters Your agent has access to your files, messages, maybe your whole machine. One malicious skill can: - Read your secrets and send them elsewhere - Modify your agent's behavior permanently - Use your identity to spread to other systems **Trust, but verify.** Scan before you install.

Frequently asked questions