Extracting RAR Firmware Images Using Unrar

Yes, unrar can be used to extract firmware images packed in RAR format because it functions as an archive decompression tool regardless of the payload inside. This article covers how to extract RAR-compressed firmware files using unrar, the core commands needed for the process, and the distinction between unpacking the RAR archive and extracting the underlying firmware filesystem.

How Unrar Handles Firmware Files

Hardware manufacturers and developers often compress raw firmware files—such as .bin, .img, or .hex files—into RAR archives to reduce file sizes for distribution.

The unrar utility operates strictly at the archive container layer. It does not inspect or modify the firmware itself; instead, it decompresses the archive and extracts the binary image onto your file system in its original form.

Commands to Extract Firmware

To extract a RAR-compressed firmware file on Linux, macOS, or Windows via the command line, use the following commands:

Extract with Original Directory Structure

To retain any internal directory hierarchy preserved within the archive, use the x (extract with full paths) command:

unrar x firmware_package.rar

Extract to a Specific Directory

To prevent cluttering your current working directory, specify a target destination folder at the end of the command:

unrar x firmware_package.rar /path/to/destination/

Extract Flattened Files

If you want to dump all files directly into the current directory without creating nested folders, use the e switch:

unrar e firmware_package.rar

Handling Split and Password-Protected Firmware

Firmware archives distributed across forums or mirrored repositories may come split into multiple parts or protected with a password:

• Split Archives: Ensure all parts (e.g., firmware.part1.rar, firmware.part2.rar) reside in the same directory. Running unrar x firmware.part1.rar automatically detects and extracts subsequent volumes.
• Password Protection: If the vendor or distributor encrypted the archive, specify the password flag:

  unrar x -p[password] firmware_package.rar

Decompressing the Archive vs. Unpacking the Firmware

While unrar successfully extracts the outer .bin or .img firmware file, it cannot decompress the contents inside the firmware image itself.

Firmware files typically contain proprietary bootloaders, kernel images, and embedded file systems (such as SquashFS, JFFS2, or UBIFS). To extract and analyze the components inside the extracted binary image, specialized reverse-engineering tools like Binwalk or firmware modification kits must be used after unrar finishes extracting the container.