browser-extension-reverse

Browser Extension Reverse Engineering

ACTION REQUIRED (execute immediately after reading)

1. NOW: Read ../field-journal/precedent-reverse.md
2. NOW: Confirm the target isbrowser extension(crx/xpi/unpacked directory), not ordinary web page JS (ordinary → js-reverse/）
3. NEXT: Unpack the extension; read manifest
4. ACT: Permission surface → background scripts → network/storage hooks

Applicable scenarios

• Chrome/Edge MV2/MV3 extension analysis
• Firefox extensions
• Malicious extension IOC, supply-chain extension poisoning investigation
• Reverse engineering of signature/encryption/proxy logic implemented by extensions

Workflow

1. Package

□ crx 解压 / 从 profile 取扩展目录
□ manifest.json：permissions、host_permissions、background、content_scripts
□ 评估过度权限（<all_urls>、webRequest、debugger）

2. Logic

□ service_worker / background 入口
□ content_script 注入点与世界（isolated）
□ chrome.storage / IndexedDB 密钥
□ 与 `js-reverse` 相同：Observe 网络与消息传递（runtime.sendMessage）

3. Dynamic

□ 开发者模式加载解压目录
□ chrome://extensions 检查错误
□ DevTools 附加 service worker
□ 必要时 Frida/浏览器 CDP（jshookmcp）

Toolchain

Tool	Purpose
Unpack/jq	manifest
Chrome DevTools	worker debugging
js-reverse toolchain	Deep JS
YARA	Malicious extension rules

Reference

• references/extension-analysis.md
• field-journal extension recovery related entries
• ../js-reverse/ ../malware-analysis/

Routing context

Upstream: MASTER R30
Downstream: Complex obfuscated JS → js-reverse; poisoning investigation → supply-chain / malware

Task completion self-check

• Are the permission surface and entry scripts listed?
• Are the key data flows reconstructed?
• Checklist？