browser-extension-reverse

browser-extension-reverse is a skill for Claude Code, Codex from zhaoxuya520/reverse-skill. It costs 34 tokens per session (571 once invoked), scanned A, original, MIT.

A guide for authorized reverse engineering of Chrome, Edge, and Firefox browser extensions. It examines an extension’s manifest, permissions, background code, injected scripts, storage, messages, and network behavior.

In plain words
What is it for?
Use it to analyze CRX, XPI, or unpacked extensions, investigate malicious extensions, inspect service workers and content scripts, and recover signing, encryption, or proxy logic.
Why use it?
Browser extensions can access websites, browser data, and traffic according to their permissions. Reviewing these parts helps explain what an extension does and identify suspicious or excessive access.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to analyze CRX, XPI, or unpacked extensions, investigate malicious extensions, inspect service workers and content scripts, and recover signing, encryption, or proxy logic.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/zhaoxuya520/reverse-skill/browser-extension-reverse
About the project

Reverse Skill is a routing package for AI coding agents that selects appropriate reverse-engineering, penetration-testing, and security-research methods and tools for a given target. It is used for tasks involving APKs, binaries, frontend JavaScript, packet captures, CTF challenges, and authorized penetration testing. Its catalogue add-ons provide the skills and instructions that guide these workflows.

zhaoxuya520/reverse-skill · 35,027 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add zhaoxuya520/reverse-skill --skill browser-extension-reverse
Clone the repo
git clone --depth 1 https://github.com/zhaoxuya520/reverse-skill

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for browser-extension-reverse

README.md
[![agentmods](https://agentmods.dev/badge/skills/zhaoxuya520/reverse-skill/browser-extension-reverse.svg)](https://agentmods.dev/skills/zhaoxuya520/reverse-skill/browser-extension-reverse)
Your own site
<a href="https://agentmods.dev/skills/zhaoxuya520/reverse-skill/browser-extension-reverse"><img src="https://agentmods.dev/badge/skills/zhaoxuya520/reverse-skill/browser-extension-reverse.svg" alt="Measured on agentmods" height="20"></a>
Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 571 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket warn 18 Jul 2026
  • Snyk pass 18 Jul 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00034 $0.00571
Opus 5 $0.00017 $0.00285
Sonnet 5 $0.00007 $0.00114
Haiku 4.5 $0.00003 $0.00057

Measured 9d ago against content hash 908c0bbcd53c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

browser-extension-reverse scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

3 near-identical copies found in the catalogue:

skills/browser-extension-reverse/SKILL.md · 74 lines

What it actually says

Browser Extension Reverse Engineering

ACTION REQUIRED(读完后立刻执行)

  1. NOW: 读取 ../field-journal/precedent-reverse.md
  2. NOW: 确认目标是浏览器扩展(crx/xpi/解压目录),不是普通网页 JS(普通 → js-reverse/
  3. NEXT: 解压扩展;读 manifest
  4. ACT: 权限面 → 后台脚本 → 网络/存储钩子

适用场景

  • Chrome/Edge MV2/MV3 扩展分析
  • Firefox 扩展
  • 恶意扩展 IOC、供应链扩展投毒调查
  • 扩展实现的签名/加密/代理逻辑还原

工作流

1. 包体

□ 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. 逻辑

□ 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. 动态

□ 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)

工具链

工具 用途
解压/jq manifest
Chrome DevTools worker 调试
js-reverse 工具链 深度 JS
YARA 恶意扩展规则

参考

  • references/extension-analysis.md
  • field-journal 扩展恢复相关条目
  • ../js-reverse/ ../malware-analysis/

路由上下文

上游: MASTER R30
下游: 复杂混淆 JS → js-reverse;投毒调查 → supply-chain / malware

任务完成自检

  • 是否列出权限面与入口脚本?
  • 是否还原关键数据流?
  • Checklist?
Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 74 lines · 34 tokens per session scan A 908c0bbcd53c

Subscribe to this mod's changes

browser-extension-reverse is a skill published in the GitHub repository zhaoxuya520/reverse-skill (35,027 stars, last pushed 5d ago), licensed MIT. It adds 34 tokens to every session and 571 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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