Hardware Hacking P3 | Linux Firmware Analysis | HackTheBox The Needle

We covered the hardware hacking challenge from HackTheBox The Needle where we analyzed a Linux firmware using Binwalk tool. Then we used grep and find commands to extract patterns of usernames and passwords and used them to login to the instance and retrieve the flag.

Challenge Description

As a part of our SDLC process, we’ve got our firmware ready for security testing. Can you help us by performing a security assessment?

Firmware Security Assessment

The task simulates a firmware security assessment. The user steps into the role of a security tester or developer tasked with:

• Downloading and analyzing firmware (firmware.binary)
• Extracting sensitive data (likely credentials)
• Logging into an instance (e.g., via Netcat) to retrieve a flag

Tools and Commands Used

File Handling & Recognition

• file firmware.binary
  Used to determine the type of firmware (e.g., Linux kernel image for ARM).

Static Firmware Analysis

• binwalk -e firmware.binary
  Extracts embedded filesystems and other data from binary firmware.
  • Binwalk detects and extracts SquashFS (compressed filesystem) images.
• Alternative Mentioned:
  unsquashfs is also referenced for manually unpacking SquashFS.

🔄 Context Update (2025):
Binwalk is still one of the top tools, but alternatives like FirmWalker, Binwalk-ng, and Firmware Analysis Toolkit (FAT) provide more automation and deeper analysis capabilities.

Content Search

• grep -rn "." -e login and grep -rn "." -e Admin
  Recursive search for strings related to potential credentials.
• find . -name sign
  Searches for a file named sign, which potentially contains the password.

🔐 These steps are aligned with the methodology of pattern-based sensitive data discovery within firmware dumps.

Connecting to the Target Instance

• Netcat (nc)
  Used to connect to a remote instance using the discovered credentials.

⚠️ Note: In modern environments, Netcat is still relevant but alternatives like socat, telnet, or even SSH may be used depending on the context.

Firmware Identification & Architecture Awareness

• Recognize architecture (ARM vs x86) early using tools like:
  • file
  • readelf
  • binwalk
• Consider emulating the firmware using QEMU or FirmAE if dynamic analysis is needed.

Static Extraction Is Only the First Step

• After extracting contents, analyze:
  • Init scripts
  • Shadow/passwd files
  • Config files
  • Embedded web UIs or binaries for hardcoded credentials.

Automation Tools Worth Noting (2025 Update)

• Firmwalker – Walks through extracted firmware for secrets.
• FAT (Firmware Analysis Toolkit) – Integrates Binwalk, QEMU, etc.
• Qiling Framework – Lightweight emulator supporting ARM, MIPS, x86.
• EMBA – Enterprise firmware scanner with CVE mapping and checks.

Credential Extraction Tips

• Use regex with grep, awk, or strings.
• Look for .htpasswd, passwd, shadow, .conf, .xml, .json, .ini.
• Search for base64 or hex-encoded strings.

Summary

Step	Action	Tool/Command	Goal
1	Identify firmware type	file firmware.binary	Detect if it’s ARM/Linux
2	Extract filesystem	binwalk -e or unsquashfs	Unpack SquashFS image
3	Search for credentials	grep -rn and find	Locate username/password
4	Connect to instance	nc <ip> <port>	Validate credentials and retrieve flag

Video Walkthrough