Mastering the 'xmount' Command (with examples)

The xmount command is a versatile tool used primarily in digital forensics and data recovery. Its main function is to facilitate on-the-fly conversion between different disk image types, allowing users to access and work with disk images in a format that suits their needs. By creating a virtual filesystem using FUSE (Filesystem in Userspace), it provides a virtual representation of input disk images, enabling seamless operations across multiple platforms and software that expect image data in certain formats.

Now, let’s explore practical use cases demonstrating how xmount can be deployed effectively.

Mount a .raw image file into a DMG container file

Code:

xmount --in raw path/to/image.dd --out dmg mountpoint

Motivation:

Creating a DMG (Disk Image) file from a RAW disk image format is often necessary for compatibility with macOS systems, as DMG is a native disk image format for macOS. When you need to analyze or manipulate disk contents on a Mac, converting to a DMG can simplify access and utilization of the image file.

Explanation:

• --in raw: This argument specifies the input format of the disk image, which in this case is a RAW image. RAW images are bit-for-bit copies of disks and contain no metadata about filesystems, making them a straightforward choice for forensic examination.

• path/to/image.dd: This is the path to the source RAW image file that you want to convert.

• --out dmg: This argument specifies the desired output format, which here is DMG. DMG files can be mounted directly in macOS, making them highly convenient for Mac users.

• mountpoint: This is the directory where the virtual filesystem will be mounted. You can access the logical structure of the DMG file from this directory.

Example Output:

After execution, you would notice that a mount directory contains a virtual DMG representation of the RAW image. Users can access the contents of the mounted DMG file as if it were a physical device.

Mount an EWF image file with write-cache support into a VHD file to boot from

Code:

xmount --cache path/to/cache.ovl --in ewf path/to/image.E?? --out vhd mountpoint

Motivation:

Enabling write-cache support while converting an EWF (Expert Witness Format) image to a VHD (Virtual Hard Disk) file is particularly useful in scenarios where you wish to test or boot the disk image in a virtualized environment. VHD files are commonly used for virtual machines, making this conversion perfect for software testing or system analysis.

Explanation:

• --cache path/to/cache.ovl: Specifies the path to the cache overlay. This allows for temporary changes to be made without modifying the original image file, ensuring that the original evidence remains untouched.

• --in ewf: Indicates that the input file is in EWF format. EWF is a proprietary format often used in forensic imaging due to its ability to include metadata and ease of use.

• path/to/image.E??: A wildcard pattern that matches the necessary fragment parts of an EWF image, which usually spans multiple files.

• --out vhd: This option dictates that the output should be formatted as a VHD file, allowing for virtualization and testing in software like VirtualBox or Hyper-V.

• mountpoint: The location where the virtual filesystem will be created, allowing users to interact with the VHD as if it were an actual disk.

Example Output:

Upon successful execution, accessing the mountpoint directory will display a virtual VHD image that can be attached to a virtual machine, simulating the disk environment stored within the EWF image.

Mount the first partition at sector 2048 into a new .raw image file

Code:

xmount --offset 2048 --in raw path/to/image.dd --out raw mountpoint

Motivation:

In certain forensic or data recovery tasks, it’s necessary to isolate and investigate specific partitions within a disk image. By mounting the first partition starting at sector 2048 to a new RAW image, one can focus on only the relevant data without interference from other partitions.

Explanation:

• --offset 2048: This option sets the offset, in sectors, where the desired partition begins. In many disk layouts, the first partition starts at sector 2048, which can help locate the start of your desired data.

• --in raw: Specifies that the input image is in RAW format, one of the most common and straightforward disk image types.

• path/to/image.dd: The RAW file serving as the source image to be processed.

• --out raw: Specifies that the output should continue to be a RAW format, preserving the original format for subsequent analysis.

• mountpoint: The directory where the virtual representation of the selected partition will be accessible for access and inspection.

Example Output:

After executing the command, the mount directory will contain a virtual RAW file reflecting the contents of the first partition, beginning at sector 2048. This streamlines the process of partition-specific analysis and data extraction.

Conclusion:

The xmount command is an essential utility in the toolkit of any IT professional, particularly those working in digital forensics and data recovery. By offering flexible conversion and mounting options, it allows users to maneuver between different disk image formats and access critical data quickly and efficiently. By following the examples discussed, users can adapt xmount for various tasks, showcasing its practicality and effectiveness in real-world scenarios.