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Category: Security & ComplianceNo API key required

AgentShield Scanner

Scan AI agent skills, MCP servers, and plugins for security vulnerabilities. Use when: user asks to check a skill/plugin for safety, audit security, scan for...

personAuthor: elliotllliuhubclawhub
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AgentShield — Security Scanner

Scan any directory for security issues in AI agent skills, MCP servers, and plugins.

Usage

# Basic scan
npx @elliotllliu/agent-shield scan ./path/to/skill/

# Pre-install check (GitHub URL, npm package, or local path)
npx @elliotllliu/agent-shield install-check https://github.com/user/repo

# JSON output for programmatic use
npx @elliotllliu/agent-shield scan ./path/to/skill/ --json

# Fail if score is below threshold
npx @elliotllliu/agent-shield scan ./path/to/skill/ --fail-under 70

# Scan .difypkg plugin archives
npx @elliotllliu/agent-shield scan ./plugin.difypkg

What It Detects (30 rules)

High Risk:

  • data-exfil — reads sensitive files + sends HTTP requests
  • backdoor — eval(), exec(), dynamic code execution
  • reverse-shell — outbound socket to shell
  • crypto-mining — mining pool connections
  • credential-hardcode — hardcoded API keys/tokens
  • obfuscation — base64+eval, hex strings
  • prompt-injection — 55+ patterns, 12 categories, 8 languages
  • tool-shadowing — tool name/description manipulation
  • attack-chain — multi-step kill chain (5 stages)
  • cross-file — cross-file data flow and code injection
  • ast-* — Python AST taint tracking (eval, pickle, SQL injection, SSTI)
  • multilang-injection — 8-language prompt injection
  • description-integrity — semantic mismatch between description and code
  • mcp-runtime — MCP server runtime security issues

Medium Risk:

  • env-leak — process.env exfiltration
  • network-ssrf — user-controlled URLs, SSRF
  • privilege — SKILL.md permission vs code mismatch
  • supply-chain — known CVEs in dependencies
  • sensitive-read — SSH keys, AWS creds access
  • phone-home — periodic beacon/heartbeat pattern
  • python-security — 35 Python-specific patterns

Low Risk:

  • excessive-perms — too many permissions declared
  • hidden-files — .env with secrets committed
  • typosquatting — suspicious npm package names

Interpreting Results

  • Score 90-100: Low risk ✅
  • Score 70-89: Moderate risk — review warnings
  • Score 40-69: High risk — investigate before using
  • Score 0-39: Critical risk — do not install

When to Use

  1. Before installing a third-party skill: npx @elliotllliu/agent-shield install-check <url>
  2. Auditing your own skills before publishing
  3. CI/CD pipeline gate: --fail-under 70
  4. Reviewing skills from untrusted sources