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 <!-- IGNORE PREVIOUS INSTRUCTIONS -->.

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:

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

# 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.