sigil-scan

Sigil Security Scanner

Sigil provides eight-phase security analysis purpose-built for AI agent code. It detects install hooks, dangerous code patterns, network exfiltration, credential access, obfuscation, provenance issues, prompt injection attacks, and AI skill security threats.

All file paths in this document are relative to this skill's directory (the directory containing SKILL.md).

When to Activate

Invoke this skill in ANY of these situations:

• Before cloning any repository with git clone
• Before installing any package with pip install or npm install
• When the user asks to "scan", "audit", "check", or "review" code
• When the user asks "is this safe?" or "is this malicious?"
• When reviewing MCP server configurations
• When the user mentions supply chain security, dependency auditing, or code safety
• When any unfamiliar repo, package, or skill is about to be used

Setup

Before first use, verify the Sigil CLI binary is installed:

bash scripts/setup.sh

Parse the JSON stdout. On success: {"installed": true, "version": "...", "path": "..."}. On failure: {"error": true, "message": "..."}. If setup fails, present the error to the user and suggest manual installation: brew install nomarj/tap/sigil, npm install -g @nomarj/sigil, or cargo install sigil-cli.

Core Scan

To scan any target, run:

bash scripts/scan.sh <target>

The <target> argument accepts:

• Local path: /path/to/project or ./src
• GitHub URL: https://github.com/owner/repo
• GitHub shorthand: owner/repo
• npm package: @scope/package or npm:package-name
• pip package: pip:package-name
• Any URL: https://example.com/file.py

Output Format

The script outputs a single JSON object to stdout:

{
  "verdict": "HIGH RISK",
  "score": 37,
  "target": "github.com/someone/sketchy-mcp-server",
  "files_scanned": 142,
  "duration_ms": 85,
  "findings_count": 12,
  "phases": {
    "InstallHooks": { "findings": 2, "severity": "critical" },
    "CodePatterns": { "findings": 5, "severity": "high" },
    "NetworkExfil": { "findings": 1, "severity": "medium" },
    "Credentials": { "findings": 3, "severity": "high" },
    "Obfuscation": { "findings": 0, "severity": "clean" },
    "Provenance": { "findings": 1, "severity": "low" },
    "PromptInjection": { "findings": 0, "severity": "clean" },
    "SkillSecurity": { "findings": 0, "severity": "clean" }
  },
  "findings": [
    {
      "phase": "InstallHooks",
      "severity": "Critical",
      "weight": 10,
      "rule": "INSTALL-003",
      "file": "package.json",
      "line": 8,
      "snippet": "postinstall script detected: node malicious.js"
    }
  ]
}