Forensic Imaging Tools: Capturing Digital Evidence with Precision

Forensic imaging, sometimes known as digital forensic imaging, is a crucial part of the modern investigative process. This highly technical field revolves around the capture and use of digital evidence in a precise and accurate manner. It's a component that often forms an essential part of an Incident response plan, something every organization should have in place for effective cybersecurity incident handling. Understanding the tools and techniques involved can help you use these methods more effectively and improve your Incident response strategy.

In this blog post, we're going to explore some prominent forensic imaging tools, look at how these tools assist in capturing digital evidence with precision, and analyze how they can be perfectly integrated into an organization's Incident response plan.

What is Forensic Imaging?

Forensic imaging involves creating an exact copy or snapshot of a storage medium, such as a hard drive, for investigation and evidence collection purposes. Unlike a regular backup or copy, a forensic image records every single bit of data on the drive, including deleted files, traces of previous file versions, and other unseen or unallocated data.

Importance of Forensic Imaging in an Incident Response Plan

An Incident response plan is vital for preparing for, and effectively dealing with cybersecurity incidents when they occur. Incorporating forensic imaging into your Incident response plan is crucial because it allows you to recover, examine, and analyze data post-incident. The forensic image serves as reliable evidence when conducting a post-incident analysis or undergoing legal procedures, ensuring nothing is overlooked or destroyed.

Key Forensic Imaging Tool: FTK Imager

Forensic Toolkit Imager (FTK Imager) is a forensic imaging tool provided by AccessData that allows investigators to examine a drive without modifying any data on it. You can use the tool to create forensic images of computer drives and other types of digital storage devices, making it valuable in Incident response and discovery processes.

Key Forensic Imaging Tool: Guymager

Guymager is an open-source tool for forensic imaging. It features a user-friendly interface and is capable of multiple parallel imaging. Moreover, it supports a variety of information storage formats, including AFF (Advanced Forensic Format), E01 (Encase Image File Format), and raw format.

Key Forensic Imaging Tool: dd

The Unix tool 'dd' is a simple but powerful tool often used in digital forensics for imaging tasks. Despite its simplicity, it's very versatile and can copy data from one file or block device (like a disk or disk partition) to another, making it invaluable.

Key Forensic Imaging Tool: DC3DD

DC3DD is a patched version of GNU dd with a number of improvements and additions. It features pattern writing, automatic splitting of output files, MD5 and SHA-1 hashing on the fly, and more. Its extensive capabilities make it a prefered tool for many forensic investigators.

Forensic Imaging Tool Considerations

Every tool has its unique features and considerations. Your choice of forensic imaging tool should depend on factors like your organization's size, the kind of data your business deals with, and the complexity of the cases you are likely to encounter, among others.

In conclusion, an effective Incident response plan calls for the inclusion of precise and accurate forensic imaging tools and techniques. When selecting these tools, it’s key to consider their features, ease of use, support provided, and compatibility with your business environment. The tools mentioned in this post are by no means exhaustive but do provide an excellent starting point for organizations looking to enhance their digital forensic capabilities. Therefore, understanding the technical aspects of these tools is integral in closing the gaps in your Incident response plan and ensuring the execution of efficient and effective digital forensics.

Acquisition and Imaging Are Not Quite the Same

The terms get used loosely. Acquisition is the whole act of capturing evidence from a source — which might be a disk, a memory chip, a cloud account or a live system. Imaging is the specific case of producing a bit-for-bit copy of storage media.

The distinction matters because not everything can be imaged. A running machine's RAM is acquired, not imaged, and the moment it powers down that evidence is gone — which is why order of volatility drives the sequence: memory first, then disk. Cloud data is acquired through APIs and account exports, with no physical media to copy at all.

Write Blockers: the Step Before the Tool

Before any imaging tool runs, the evidence drive should be behind a write blocker. Connecting a disk to a running operating system can update timestamps and mount records without anyone touching a file, and that alone is enough to put an acquisition in question.

Hardware write blockers sit inline and physically prevent writes. Hardware duplicators go further, combining the block with a dedicated imaging engine that copies faster than a workstation and produces the verification hash as it goes. Software write blocking works and is sometimes the only option in the field, but hardware is the defensible default.

Whichever route: hash on acquisition, verify before analysis, verify again afterwards, and record all three. An image nobody can prove is unaltered is not evidence.

Where to go next

This guide covers general-purpose forensic tooling. Three companion guides go deeper on the jobs that have their own toolsets:

• Free and open-source forensics software — what the no-budget stack actually covers, and where it stops.
• Mobile device forensics tools — phone and tablet extraction, which is a different discipline with different hardware.
• Digital forensics tools — the analysis stage, once the image exists.