extension-analyze

name	extension-analyze
description	Audit Chrome extensions for security issues, best practice violations, performance problems, and CWS compliance. Scans manifest, code, CSP, message handlers, storage, and dependencies.

Extension Analyze (Security & Compliance Auditor)

Audit an existing Chrome extension. Do NOT just explain — execute the workflow.

Workflow (Execute This)

Step 1: Locate extension root and detect framework

Ask user for path if not provided. Detect framework:

ls wxt.config.ts plasmo.config.ts vite.config.ts manifest.json 2>/dev/null

• Plasmo: manifest auto-generated; check package.json and plasmo.config.ts instead
• WXT: check wxt.config.ts manifest section
• Vanilla/CRXJS: check manifest.json directly

Step 2: Scan manifest.json (or equivalent config)

# Check MV version, permissions, host_permissions, CSP, web_accessible_resources
cat <ext>/manifest.json | jq '{manifest_version, permissions, host_permissions, content_security_policy, web_accessible_resources}'

Step 3: Quick grep scans

# XSS vectors
grep -rn "innerHTML\|outerHTML\|document\.write\|insertAdjacentHTML" <ext>/src --include="*.ts" --include="*.js"

# Unsafe patterns
grep -rn "eval(\|new Function(\|setTimeout.*string\|setInterval.*string" <ext>/src

# Hardcoded secrets
grep -rn "api_key\|apiKey\|secret\|password\|token" <ext>/src --include="*.ts" --include="*.js" | grep -v "\.test\." | grep -v "node_modules"

# HTTP (non-HTTPS) calls
grep -rn "http://" <ext>/src --include="*.ts" --include="*.js"

# Message handler sender validation
grep -rn "onMessage\|addListener" <ext>/src | grep -v "node_modules"

# Remote code loading
grep -rn "importScripts\|fetch.*\.js\|eval\|chrome\.scripting\.executeScript" <ext>/src

Step 4: Check CSP configuration

• MV3 default CSP: script-src 'self'; object-src 'self'
• Flag any unsafe-inline, unsafe-eval, or http: sources
• Verify no remote script sources

Step 5: Dependency audit

cd <ext> && npm audit --json | jq '.vulnerabilities | to_entries[] | {pkg: .key, severity: .value.severity}'

Step 6: Generate report

Output findings grouped by severity. See Output Format below.

---

Severity Levels

Level	Criteria
Critical	RCE, data exfiltration, remote code loading, eval with untrusted input
High	XSS, missing sender validation, API keys in source, HTTP API calls
Medium	Overly broad permissions, unsafe-inline CSP, sync storage secrets
Low	Missing error handling, no TypeScript, console.log in production

---

Top 10 Issues Found in Most Extensions

1. innerHTML with page-sourced data (XSS) — High
2. onMessage without sender origin check — High
3. <all_urls> host permission when not needed — Medium
4. unsafe-inline or unsafe-eval in CSP — Medium/Critical
5. API keys hardcoded in source — Critical
6. eval() or new Function() usage — Critical
7. chrome.storage.sync storing sensitive data — Medium
8. HTTP endpoints instead of HTTPS — High
9. Remote script loading (MV3 violation) — Critical
10. Missing web_accessible_resources restrictions — Medium

---

Output Format

## Extension Audit Report: <name> v<version>
Date: <date> | MV: <2|3>

### Summary
Critical: X | High: X | Medium: X | Low: X

### Findings

#### [CRITICAL] API Key Exposed in Source
File: src/background.ts:42
Pattern: `const API_KEY = "sk-..."`
Fix: Move to environment variable or user-provided settings
Reference: references/common-vulnerabilities.md#4

...

### Passed Checks
- CSP: No unsafe-inline/eval ✓
- HTTPS: All API calls use HTTPS ✓

---

References

• references/security-checklist.md — Full security audit checklist
• references/best-practices-checklist.md — Performance, UX, accessibility, CWS
• references/common-vulnerabilities.md — Vulnerability patterns with grep/fix
• references/cws-compliance-checklist.md — Chrome Web Store policy compliance
• Chrome Permissions List
• Chrome Extensions Docs

Related Skills

• extension-manifest — Generate/validate manifest.json
• extension-create — Scaffold new extension
• extension-publish — Store submission checklist