The burgeoning field of digital forensics plays a crucial role in investigating a wide range of cybercrimes and cybersecurity incidents. Indeed, in our technology-centric world, even “traditional” crime investigations often include a piece of digital evidence waiting to be recovered and analyzed.
This art of discovering, analyzing and interpreting digital evidence has seen substantial growth, particularly in investigations involving various types of fraud and cybercrime, tax evasion, stalking, child exploitation, intellectual property theft and even terrorism. Additionally, computer forensics techniques help organizations understand the scope and impact of data breaches, as well as prevent further harm from these incidents.
With this in mind, digital forensics has a role to play in various contexts, including criminal investigations, incident response, divorce and other legal proceedings, employee misconduct investigations, counter-terrorism work, fraud detection and recovery of data.
Let’s now analyze how exactly digital forensic investigators evaluate the digital crime scene, look for clues and piece together the story the data has to tell
1. Collection of evidence
First, it’s time to get your hands on the evidence. This phase involves identifying and collecting sources of digital evidence, as well as creating exact copies of information that may be linked to the incident. In fact, it is important to avoid modifying the original data and, with the help of suitable tools and devices, create copies bit by bit.
Analysts are then able to recover deleted files or hidden partitions of the disk, ultimately generating an image the same size as the disk. Labeled with date, time and time zone, samples must be isolated in containers that protect them from the elements and prevent deterioration or deliberate tampering. Photos and notes documenting the physical state of devices and their electronic components often help provide additional context and help understand the conditions under which the evidence was collected.
Throughout the process, it is important to adhere to strict measures such as the use of gloves, anti-static bags and Faraday cages. Faraday cages (boxes or bags) are particularly useful with devices sensitive to electromagnetic waves, such as cell phones, to ensure the integrity and credibility of evidence and prevent data corruption or tampering.
In line with the order of volatility, sample acquisition follows a systematic approach – from most volatile to least volatile. As also stated in the Internet Engineering Task Force (IETF) RFC3227 guidelines, the initial step involves gathering potential evidence, from data relevant to memory and cache contents and continuing through to data on archival media.
2. Data retention
To lay the foundation for successful analysis, the information collected must be safeguarded from damage and tampering. As previously noted, the actual analysis should never be performed directly on the seized sample; instead, analysts must create forensic images (or exact copies or replicas) of the data on which the analysis will then be conducted.
As such, this phase revolves around a “chain of custody,” which is a meticulous record documenting the location and date of the sample, as well as who exactly interacted with it. Analysts use hashing techniques to unambiguously identify files that could be useful to investigations. By assigning unique identifiers to files via hashes, they create a digital fingerprint that helps track and verify the authenticity of evidence.
Simply put, this phase is designed not only to protect the data collected but, through the chain of custody, also to establish a meticulous and transparent framework, all while leveraging advanced hashing techniques to ensure the accuracy and reliability of the analyses.
3. Analysis
Once the data has been collected and its conservation has been ensured, it is time to move on to the heart of the matter and the truly technological part of the investigative work. This is where specialized hardware and software come into play as investigators delve into the collected evidence to draw meaningful insights and conclusions about the incident or crime.
There are various methods and techniques to guide the “game plan”. Their actual choice will often depend on the nature of the investigation, the data examined, as well as the expertise, industry-specific knowledge and experience of the analyst.
Indeed, digital forensics requires a combination of technical expertise, investigative acumen, and attention to detail. Analysts must stay abreast of evolving technologies and cyber threats to remain effective in the highly dynamic field of digital forensics. Furthermore, having clarity on what you are actually looking for is equally crucial. Whether discovering malicious activity, identifying cyber threats or supporting legal proceedings, the analysis and its outcome are based on well-defined objectives of the investigation.
Reviewing timelines and access logs is a common practice during this phase. This helps reconstruct events, establish sequences of actions and identify anomalies that could be indicative of malicious activity. For example, examining RAM is critical to identifying volatile data that may not be stored on disk. This may include active processes, encryption keys, and other volatile information relevant to the investigation.
4. Documentation
All actions, artifacts, anomalies and any patterns identified prior to this phase must be documented in as much detail as possible. In fact, the documentation should be detailed enough to allow another forensic expert to replicate the analysis.
Documenting the methods and tools used during the investigation is critical for transparency and reproducibility. It allows others to validate the results and understand the procedures followed. Investigators should also document the reasons behind their decisions, especially if they encounter unexpected challenges. This helps justify the actions taken during the investigation.
In other words, meticulous documentation is not just a formality, but is a fundamental aspect to maintain the credibility and reliability of the entire investigative process. Analysts must adhere to best practices to ensure their documentation is clear, thorough, and compliant with legal and forensic standards.
5. Reporting
Now is a good time to summarize the findings, processes and conclusions of the investigation. An executive report is often written first, outlining the key information clearly and concisely, without going into technical details.
Subsequently, a second report called “technical report” is drawn up in which the analysis carried out is detailed, highlighting techniques and results, leaving aside judgements.
Therefore, a typical digital forensics report:
- provides basic information about the case,
- defines the scope of the investigation together with its objectives and limits,
- describes the methods and techniques used,
- details the process of acquiring and preserving digital evidence,
- presents the results of the analysis, including discovered artifacts, timelines and models,
- summarizes the results and their meaning in relation to the objectives of the investigation
Let’s not forget: the report must adhere to legal standards and requirements so that it can withstand legal scrutiny and serve as a crucial document in legal proceedings.
With technology becoming increasingly intertwined in various aspects of our lives, the importance of digital forensics in different fields is set to grow further. Just as technology evolves, so too do the methods and techniques used by malicious actors who are always intent on obscuring their activities or misleading digital detectives. Digital forensics must continue to adapt to these changes and use innovative approaches to stay ahead of cyber threats and ultimately help ensure the security of digital systems.