skill-guard

# 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 Snyk Agent Scan (the renamed successor to `mcp-scan`) to analyze what's actually in the skill, catches AI-specific threats, and blocks install if issues are found. If the scanner is unavailable or not configured, the wrapper now reports that separately instead of pretending the skill itself is malicious.

## 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 Snyk Agent Scan** — Snyk's security scanner for AI agents
3. **Blocks or installs** — clean skills get installed, threats get quarantined

## What It Catches

Real exampl...