appfinger

AppFinger

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AppFinger is a fast HTTP application fingerprint scanner and Go library. It fetches web banners, headers, titles, certificates, favicon hashes, and client-side redirects, then matches them against YAML fingerprint rules.

Rules are maintained separately in hexbay/finger-rules.

✨ Features

• 🌐 HTTP banner and response fingerprinting
• 🎯 Header, body, title, status code, certificate, favicon hash, and body hash matching
• 🔁 HTTP redirect, meta refresh, and lightweight JavaScript redirect handling
• ⚡ Concurrent target scanning
• 🧰 Optional proxy, timeout, stdin, file input, and JSON output
• 🧱 WordPress plugin and theme enhancement detection
• ✅ Strict rule validation mode
• 🧪 Usable both as a CLI and as a Go library

📦 Installation

Build from source:

git clone https://github.com/hexbay/appfinger.git
cd appfinger
go build -o appfinger .

Or install with Go:

go install github.com/hexbay/appfinger@latest

🚀 Quick Start

Scan one target:

appfinger -u https://example.com

Scan multiple targets:

appfinger -u https://example.com -u https://example.org

Scan from a file:

appfinger -l urls.txt -t 30 -o result.json -output-format json

Scan from stdin:

cat urls.txt | appfinger -s

Use an HTTP proxy:

appfinger -u https://example.com -x http://127.0.0.1:7890

⚙️ CLI Options

APPFINGER:
  -u, -url string[]          Target URL to scan (-u INPUT1 -u INPUT2)
  -l, -url-file string       File containing URLs to scan
  -s, -stdin                 Read URLs from stdin
  -t, -threads int           Number of concurrent threads (default 10)
  -timeout int               Timeout in seconds (default 10)
  -x, -proxy string          HTTP proxy, e.g. http://127.0.0.1:7890
  -d, -finger-home string    Fingerprint YAML directory
  -ur, -update-rule          Update rules from the finger-rules repository
  -di, -disable-icon         Disable favicon fetching and icon hash matching
  -dj, -disable-js           Disable JavaScript redirect parsing
  -debug-req                 Dump HTTP requests
  -debug-resp                Dump HTTP responses
  -v, -version               Show version
  -validate                  Validate rules and exit

OUTPUT:
  -o, -output string         File to write output to
  -output-format string      Output format: txt or json (default txt)

HELP:
  -debug                     Enable debug logs

🧩 Rule Repository

AppFinger uses YAML rules from finger-rules. When the default rule directory does not exist, AppFinger initializes it automatically by downloading finger-rules.

Update the local rule repository:

appfinger -update-rule

Use a custom rule directory:

appfinger -u https://example.com -d /path/to/finger-rules

Validate rules before scanning:

appfinger -validate -d /path/to/finger-rules

🛠️ Library Usage

package main

import (
	"context"
	"fmt"

	"github.com/hexbay/appfinger/pkg/fetch"
	"github.com/hexbay/appfinger/pkg/rule"
	"github.com/hexbay/appfinger/pkg/runner"
)

func main() {
	fetcher := fetch.NewFetcher(fetch.DefaultOption())

	manager, err := rule.LoadDefaultRules(context.Background())
	if err != nil {
		panic(err)
	}

	r, err := runner.NewRunner(fetcher, manager, &runner.Options{
		Threads: 10,
		Timeout: 10,
	})
	if err != nil {
		panic(err)
	}
	defer r.Close()

	result, err := r.Scan("https://example.com")
	if err != nil {
		panic(err)
	}

	fmt.Printf("%#v\n", result.Components)
}

🔎 How It Works

AppFinger fetches target HTTP responses and normalizes useful matching data into banners. The rule engine then evaluates YAML matchers against response parts such as body, headers, title, certificate, favicon hash, and status code.

🧪 Development

Run tests:

go test ./...

Build locally:

go build ./...

🤝 Contributing

Issues and pull requests are welcome. If you add or modify fingerprint behavior, please include focused tests where possible.

📄 License

AppFinger is licensed under the MIT License. See LICENSE for details.