Hackbrowser Mcp

The first browser MCP built for security testing.

Other browser MCPs let your AI fill forms and take screenshots. This one lets it find vulnerabilities.

What It Does • How It's Different • Quick Start • Examples • Tools • Architecture

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What It Does

hackbrowser-mcp gives your AI agent a real Firefox browser and 39 security testing tools via the Model Context Protocol. The agent can launch the browser, browse a target, capture all traffic, and test for vulnerabilities — all through natural language.

You: "Log in as admin and as a regular user. Find endpoints the user shouldn't access."

Agent: → launches Firefox
       → creates two isolated containers (admin + user)
       → logs in both accounts
       → browses the app, captures traffic
       → compares responses across roles
       → "User can access GET /api/admin/users — should return 403, returns 200"

The AI handles the entire workflow: launching the browser, managing sessions, discovering endpoints, testing parameters, and generating a security report. You describe what to test. It does the rest.

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How It's Different

There are dozens of browser MCPs. They all do the same thing: let an LLM navigate pages, click buttons, and extract text. They're built for automation — filling forms, scraping data, running UI tests.

None of them can test for vulnerabilities. That's the gap hackbrowser-mcp fills.

Other Browser MCPs hackbrowser-mcp

Purpose Web automation, scraping, form filling Security testing, vulnerability assessment

Sessions Single session 2-4 isolated containers with separate cookies, storage, and auth

Traffic Read-only network tab (if any) Full HAR capture + replay with modifications

Security tools None 14 tools: injection testing, CSRF, IDOR, access matrix, report generation

Injection testing Not possible 7 types, 60+ payloads, technique-labeled results

Access control Not possible Cross-role comparison, endpoint access matrix, IDOR detection

Browser Chromium (CDP) Firefox (WebDriver BiDi) — different engine catches different bugs

Anti-detection Varies Stealth mode built-in (fingerprint, UA, WebGL spoofing)

Specific comparisons with popular projects

| Project | Stars | What it does | What it can't do | |---|---|---|---| | playwright-mcp | 29k | Navigate, click, type, screenshot via accessibility tree | No multi-session, no traffic capture, no security testing | | browser-use | 81k | AI completes web tasks (shopping, forms, research) | Single agent action, no HAR, no injection testing | | stagehand | 22k | act/extract/observe SDK for browser automation | No security tools, no container isolation | | chrome-devtools-mcp | 29k | DevTools debugging, performance analysis, network monitoring | Read-only network, no replay, no active testing | | browser-tools-mcp | 7k | Console, network, audit monitoring for coding agents | IDE-focused, no offensive testing capability | | mcp-playwright | 5k | Multi-browser test automation + scraping | No security awareness, no access control analysis |

All of these are excellent tools for their intended purpose. hackbrowser-mcp doesn't replace them — it serves a completely different use case.

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Core Capabilities

Multi-Container Isolation

Run 2-4 browser sessions simultaneously, each with completely isolated state. This is the foundation for access control testing.

┌────────────────────────────────────────────────────────┐
│                     Firefox Instance                    │
├───────────────┬───────────────┬────────────────────────-┤
│  Container 1  │  Container 2  │  Container 3            │
│  role: admin  │  role: user   │  role: guest             │
│               │               │                         │
│  cookies: A   │  cookies: B   │  cookies: none          │
│  storage: A   │  storage: B   │  storage: none          │
│  session: ✓   │  session: ✓   │  session: ✗             │
└───────────────┴───────────────┴─────────────────────────┘

compare_access → "GET /api/admin/users returns 200 for user (expected 403)"
access_matrix  → role × endpoint grid showing every authorization gap

Traffic Intelligence

Every HTTP request and response is captured, stored, and queryable. Replay any request with modifications.

Browser → Network Interceptor → In-Memory Store (10K max, FIFO)
                                       │
                             ┌─────────┴──────────┐
                             │                     │
                       Auto-save (60s)       Replay / modify
                             │                     │
                             ▼                     ▼
                       HAR file (disk)      replay_request
                             │              (change method,
                       Resume on restart     headers, body)

Active Security Testing

Discover injection points from captured traffic, then test them with 60+ payloads across 7 vulnerability types.

| Type | Payloads | Techniques | |------|----------|------------| | SQLi | 9 | Error-based, union, time-based blind (MSSQL/MySQL/Postgres), boolean-blind | | XSS | 8 | Reflected script, event handler, SVG, JS context, HTML5 events, iframe | | SSTI | 8 | Jinja2, Freemarker, ERB, Angular sandbox, Spring EL, Vue | | SSRF | 8 | Localhost variants (IPv4/v6/hex/octal), AWS/GCP/Azure metadata, DNS rebind | | CMDi | 8 | Semicolon, pipe, backtick, subshell, newline, quote-break | | LFI | 8 | Path traversal, double-dot, /proc/environ, PHP filter, double-encode | | HTML Injection | 6 | Tag injection, form injection, style overlay, meta redirect |

When built-in payloads get blocked, the AI agent analyzes the WAF response and crafts custom bypass payloads using replay_request.

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Quick Start

Install

git clone https://github.com/user/hackbrowser-mcp.git
cd hackbrowser-mcp
bun install

Connect to your AI agent

Claude Desktop / Claude Code

Add to your MCP config (~/.claude/claude_desktop_config.json):

{
  "mcpServers": {
    "hackbrowser": {
      "command": "bun",
      "args": ["run", "/path/to/hackbrowser-mcp/src/index.ts", "--mcp"]
    }
  }
}

Cursor / Continue / other MCP clients

Same config format. Point the command to your installation path.

Standalone (no AI agent)

bun run src/index.ts --launch              # GUI mode
bun run src/index.ts --launch --headless   # headless
bun run src/index.ts --mcp                 # MCP server (stdio)

Start testing

You: "Launch the browser and scan https://target.com for vulnerabilities"

That's it. The agent handles the rest.

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Workflow Examples

Full Security Scan

You: "Crawl https://app.com, find injection points, test them, generate a report."

Agent: browser_launch → navigate → crawl (100 pages)
       → find_injection_points → test_injection (SQLi, XSS)
       → test_csrf → test_rate_limit
       → generate_report
       → "Found 3 XSS, 1 SQLi, 2 missing CSRF tokens"

IDOR / Access Control Audit

You: "Login as admin and regular user. Find what the user shouldn't access."

Agent: container_setup (admin + user) → container_login (both)
       → navigate admin pages → compare_access
       → access_matrix
       → "User can reach GET /api/admin/users (200 instead of 403)"

WAF Bypass

You: "Test the search param for XSS. Bypass any WAF."

Agent: test_injection {types: ["xss"]} → all blocked
       → analyzes response:  stripped, events filtered
       → replay_request with  → REFLECTED
       → "Confirmed XSS via HTML5 ontoggle event bypass"

Offline HAR Analysis

You: "Import this HAR file and find injection candidates."

Agent: import_har → get_endpoints (87 found)
       → find_injection_points (23 candidates)
       → test_injection → "2 reflected XSS confirmed"

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Tools Reference (39 tools)

Browser Control (3)

| Tool | Description | |------|-------------| | browser_launch | Launch Firefox with managed profile | | browser_close | Close browser, auto-export HAR | | browser_status | Protocol, containers, tab count, captured requests |

Containers (3)

| Tool | Description | |------|-------------| | container_setup | Create 1-4 containers with roles and credentials | | container_login | Login for a container (programmatic or manual) | | container_list | List containers with auth status |

Navigation (4)

| Tool | Description | |------|-------------| | navigate | Go to URL in a container tab | | go_back / go_forward | Browser history navigation | | wait_for | Wait for selector, URL, network idle, or JS condition |

Interaction (7)

| Tool | Description | |------|-------------| | click | Click by CSS selector or text content | | type_text | Type into input fields | | select_option | Select dropdown value | | submit_form | Submit a form | | scroll | Scroll page or element | | hover | Hover over element | | press_key | Keyboard keys (Enter, Tab, Escape, etc.) |

Page Inspection (4)

| Tool | Description | |------|-------------| | screenshot | Capture PNG screenshot | | get_page_source | Full HTML source | | get_dom_tree | Simplified DOM tree (LLM-friendly) | | evaluate_js | Execute JavaScript and return result |

Traffic Capture (5)

| Tool | Description | |------|-------------| | get_requests | List captured requests with filters (URL, method, status, MIME) | | get_response | Full request/response details by ID | | get_endpoints | Auto-discovered API endpoints with parameter templates | | export_har | Save traffic as HAR 1.2 file | | import_har | Load HAR from previous session |

Security Analysis (4)

| Tool | Description | |------|-------------| | compare_access | Cross-container IDOR / broken authorization detection | | access_matrix | Role x endpoint access grid | | find_injection_points | Identify injectable params across 10 vuln types | | replay_request | Replay with modified method, headers, body, URL |

Active Testing (3)

| Tool | Description | |------|-------------| | test_injection | 7 types, 60+ payloads, technique-labeled results | | test_csrf | Replay without CSRF tokens | | test_rate_limit | Rapid-fire requests, check for 429 |

Auth Detection (3)

| Tool | Description | |------|-------------| | detect_auth | Check session validity | | detect_login_form | Find login form fields and CSRF token | | auto_login | Auto-fill and submit login |

Discovery (2)

| Tool | Description | |------|-------------| | crawl | BFS spider with form discovery and API extraction | | get_sitemap | Return crawl results |

Reporting (1)

| Tool | Description | |------|-------------| | generate_report | Security report (markdown/HTML) with findings and evidence |

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Library Usage

Use hackbrowser-mcp as a TypeScript library for custom tooling:

import {
  launchFirefox, closeFirefox,
  NetworkInterceptor, BrowserInteraction, Crawler,
  extractEndpoints, findInjectionPoints, testInjection,
  compareAccess, generateReport,
  buildHar, saveHar, loadHar,
} from "hackbrowser-mcp";

// Offline HAR analysis
const har = await loadHar("./capture.har");
const requests = harEntriesToRequests(har.log.entries);
const endpoints = extractEndpoints(requests);
const points = findInjectionPoints(requests);

console.log(`${endpoints.length} endpoints, ${points.length} injection candidates`);

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Architecture

src/
├── browser/                 Firefox control
│   ├── bidi-client.ts       WebDriver BiDi protocol
│   ├── cdp-client.ts        CDP fallback
│   ├── launcher.ts          Binary detection + profile setup
│   ├── container-manager.ts Container isolation + extension WS
│   ├── interaction.ts       Click, type, scroll, hover
│   ├── crawler.ts           BFS spider
│   └── auth-detector.ts     Session detection
├── capture/                 Traffic
│   ├── network-interceptor.ts  Capture + auto-save (10K cap)
│   ├── har-builder.ts          HAR 1.2 builder
│   └── har-storage.ts          HAR I/O + merge
├── analysis/                Security engines
│   ├── active-tester.ts     60+ injection payloads
│   ├── injection-mapper.ts  Param → vuln type mapping
│   ├── endpoint-extractor.ts  API endpoint discovery
│   ├── container-differ.ts  Cross-role comparison
│   ├── access-matrix.ts     Role x endpoint matrix
│   └── report-generator.ts  Report formatting
├── protocol/
│   ├── tools.ts             39 tool definitions (Zod schemas)
│   └── mcp-server.ts        MCP stdio transport
└── types/                   TypeScript types

Design decisions:

• Firefox + BiDi first — Native Firefox protocol. Different rendering engine catches bugs Chrome-based tools miss. CDP available as fallback.
• Container isolation — Firefox Multi-Account Containers for true session separation. Not separate browser instances.
• Server-side fetch for testing — Active testing uses fetch() outside the browser to avoid polluting browser state.
• HAR 1.2 standard — Import/export for session continuity. Auto-save every 60s, resume on restart.
• Memory-bounded — 10K entry cap with FIFO eviction. 30s fetch timeout.
• Stealth by default — navigator.webdriver, UA, plugins, WebGL fingerprint all spoofed.

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Limitations

• Firefox only (container isolation requires Firefox Multi-Account Containers)
• macOS / Linux (Windows not tested)
• One Firefox instance per port
• WebSocket frames not captured (only upgrade request)

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For authorized security testing only. Always obtain proper permission before testing any application.

MIT License • Built with Bun + TypeScript

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: badchars
• Source: badchars/hackbrowser-mcp
• License: MIT
• Homepage: https://github.com/badchars/hackbrowser-mcp#quick-start

Install and usage instructions live in the source repository linked above.