Binwalk

Binwalk is a powerful tool designed for analyzing, extracting, and reverse-engineering firmware images. It is frequently used by pentesters and security researchers for identifying embedded files and data in firmware, especially in IoT and hardware hacking.

Key Features

• Signature Scanning

  • Binwalk scans firmware images for known file signatures such as compressed files, file systems, and cryptographic keys.

• File Extraction

  • Automatically extracts embedded files and file systems from firmware images.

• Entropy Analysis

  • Helps detect encrypted or compressed data by analyzing the randomness within a binary.

• Custom Signatures

  • Users can define their own file signatures, expanding Binwalk's capabilities to detect specific patterns.

Cheat Sheet

# Scan a firmware image for known file signatures
binwalk firmware.bin

# Automatically extract embedded files from a firmware image
binwalk -e firmware.bin

# Analyze entropy to detect encrypted or compressed sections
binwalk -E firmware.bin

# Recursively extract files from deeply embedded archives
binwalk -Me firmware.bin

Installation

Binwalk can be easily installed on most Linux distributions using the following command:

sudo apt-get install binwalk

For other systems, or to build it from source, follow the instructions on the official Binwalk GitHub repository.

Usage

Here’s a quick breakdown of the most common commands:

1. Basic Scan: To identify and list all known signatures in a firmware image:

   binwalk firmware.bin

2. Extract Embedded Files: Automatically extract files found during the scan:

   binwalk -e firmware.bin

3. Entropy Analysis: Useful for detecting compressed or encrypted sections within the firmware:

   binwalk -E firmware.bin

4. Recursive Extraction: Extracts files recursively to dig deeper into embedded archives:

   binwalk -Me firmware.bin

Common Use Cases

• Firmware Reverse Engineering

  • Binwalk helps break down firmware to find vulnerabilities, such as hardcoded credentials or encryption keys.

• File System Extraction

  • Extract embedded file systems like JFFS2, SquashFS, etc. from IoT devices.

• Cryptanalysis

  • Identify and locate encrypted sections of firmware for further investigation.

Resources

• Binwalk Wiki