Getting Started with FTK Imager: Your Guide to Free Disk and Memory Imaging

In the world of digital forensics and incident response, getting a reliable copy of digital evidence is the crucial first step. That’s where FTK Imager comes in. It’s a widely respected and completely free tool from Exterro that lets investigators create exact duplicates—forensic images—of computer disks and capture the contents of live memory (RAM).

Whether you’re handling a security incident, performing forensic analysis, or just need to preserve data safely, understanding FTK Imager is essential.

What Exactly is FTK Imager?

Think of FTK Imager as a specialized digital photocopier for hard drives and memory. You can download it directly from the Exterro website (usually after providing some contact info). While we’re demonstrating using the Windows version, it’s important to know that FTK Imager itself must be installed and run on a Windows machine. However, from that Windows machine, you can use it to image drives from other systems, like Linux computers, provided they are connected properly (often via a write-blocker).

Its main job is to create forensic images. These aren’t just simple copies of files you can see. A forensic image is a precise, bit-for-bit duplicate of the source media. This includes everything: active files, hidden files, remnants of deleted files sitting in unallocated space, and the file slack (the unused space within a file’s last cluster). This completeness is vital because crucial evidence often hides in these less obvious areas. FTK Imager is designed to capture this data without altering the original drive, preserving the integrity of the evidence. Working from the image keeps the original source safe from accidental changes during analysis.

Key Capabilities of FTK Imager

FTK Imager isn’t just a one-trick pony; it offers several ways to capture data:

1. Physical Drive Imaging: This creates that complete bit-for-bit copy of an entire physical drive (like an HDD or SSD).
2. Logical Drive Imaging: This captures only the active file system – the files and folders you’d normally see in Windows Explorer. Keep in mind, what you capture here is limited by the user permissions active when you run the tool.
3. Image File Analysis: You can load existing forensic image files (like those you created earlier or received from someone else) to browse their contents.
4. Folder Content Imaging: Allows you to target specific folders for acquisition.
5. CD/DVD Imaging: It can also handle imaging optical media.
6. Memory Capture: Critically important for incident response, this captures the live contents of the computer’s RAM, which often holds passwords, running processes, network connections, and other volatile data that disappears when the machine is turned off.

One particularly useful feature is Image Mounting. FTK Imager lets you mount a previously captured image file as a drive letter in Windows. This mounted image is read-only, so you can browse the file system structure exactly as it was on the original device using Windows File Explorer. This is incredibly helpful for exploring files, recovering deleted items (if they haven’t been overwritten), or even running targeted scans or scripts against the image data without risk.

To ensure evidence integrity, FTK Imager uses hashing algorithms – MD5 and SHA-1. When you create an image, you can have FTK Imager calculate a hash value (like a unique digital fingerprint) for the source data and the resulting image file. If these hashes match, it proves the copy is identical and hasn’t been tampered with. This is fundamental for maintaining the chain of custody in forensic investigations.

Step-by-Step: Creating a Disk Image with FTK Imager

Before you begin, you’ll need administrator privileges on the machine where you’re running FTK Imager. If you’re imaging a drive that’s part of an active investigation, always use a hardware write-blocker to prevent any accidental writes to the original evidence drive.

1. Launch FTK Imager and Select Source: Go to File -> Create Disk Image. You’ll be asked to choose the source evidence type (Physical Drive, Logical Drive, Image File, Contents of a Folder, or Fernico Device for optical media). Select the appropriate source, often “Physical Drive” for a full forensic copy. You’ll then choose the specific drive from the list. FTK Imager displays useful details about the selected drive.

2. Configure the Image Destination and Format: Click “Add…” to specify where the image file will be saved and what format it should be.

   • Image Type: You have choices like Raw (dd), SMART, E01 (EnCase format, common in forensics), and AFF. E01 is often preferred as it includes compression and metadata storage within the image file itself. You can even create multiple image types simultaneously if needed.
   • Metadata: If you choose E01, you’ll be prompted to enter case information like case number, evidence number, examiner name, and descriptive notes. This is crucial documentation.
   • Destination: Select the folder where you want to save the image file. Crucially, never save the image file onto the same drive you are imaging. Use a separate external hard drive or network share. Give the image file a meaningful name.
   • Compression and Fragmentation: You can choose compression levels (from 0 for none to 9 for highest) to save space, though higher compression takes longer. You can also set image fragment sizes (e.g., split the image into 2GB chunks), which can be useful for older file systems or transferring files.

3. Start the Imaging Process: Once you’ve configured the destination(s), click “Finish”. Then click “Start”. FTK Imager will begin the acquisition process, showing progress and speed. This can take a significant amount of time depending on the drive size and connection speed.

4. Verification: After imaging completes, FTK Imager automatically verifies the integrity of the created image file(s) by comparing the hash value calculated during imaging with a hash calculated from the final image file. It will report whether the hashes match. Always check this verification status. The results are stored in a text file report in the same directory as the image.

Step-by-Step: Capturing Live Memory with FTK Imager

Capturing RAM is often much quicker than disk imaging but equally vital for volatile data.

1. Initiate Memory Capture: In FTK Imager, go to File -> Capture Memory.
2. Set Destination and Options: Specify the destination path and filename for the memory dump file (usually with a .mem extension or similar). You have options to:
   
   • Include pagefile.sys: This captures the Windows page file, which can contain memory swapped out to disk. This increases the capture size but can hold valuable data.
   • Create AD1 file: This saves the memory dump within an AccessData-specific container format (AD1), which might be required if you plan to use other AccessData tools for analysis. Otherwise, the raw memory dump is usually sufficient for tools like Volatility.
3. Capture: Click the “Capture Memory” button. The process is typically quite fast.

What Comes After Imaging?

FTK Imager excels at acquisition – creating those reliable disk and memory images. However, it’s not primarily an analysis tool. Once you have your E01, raw, or memory dump files, you’ll typically move on to dedicated forensic analysis platforms or tools.

For disk images, tools like Autopsy, EnCase, X-Ways Forensics, or Magnet AXIOM are used to parse file systems, carve for deleted files, search keywords, analyze artifacts (like registry hives, browser history, etc.), and build timelines.

For memory images, Volatility Framework is the standard open-source tool for extracting running processes, network connections, command history, registry keys loaded in memory, and even potentially recovering passwords or encryption keys.

Important Considerations

• Mobile Devices: FTK Imager is not designed for imaging smartphones or tablets. Mobile forensics requires specialized tools like Cellebrite, GrayKey, MSAB XRY, or Oxygen Forensic Detective.
• Imaging Speed: While drive size and connection type (USB 2 vs. USB 3 vs. SATA) are the biggest factors, FTK Imager has seen performance improvements over the years, making acquisition generally faster than it used to be.
• Write Blockers: It cannot be stressed enough – always use a reliable hardware write-blocker when connecting original evidence drives to your forensic workstation to prevent any data alteration.

Why FTK Imager Remains Essential

Even with numerous commercial forensic suites available, FTK Imager holds its place as an indispensable tool. It’s reliable, straightforward for its core tasks, compatible with industry-standard image formats, and, importantly, it’s free. For any investigator, technician, or analyst needing to safely capture disk or memory data for preservation or later analysis, FTK Imager provides a powerful and accessible solution. It’s the perfect starting point for sound digital evidence handling.