The booming 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 investigations of “traditional” crimes often include a piece of digital evidence that is waiting to be retrieved 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, theft of intellectual property and even terrorism. Additionally, digital forensic techniques also help organizations understand the scope and impact of data breachesas well as help prevent further damage caused by these incidents.
With this in mind, digital forensics has a role to play in a variety of contexts, including criminal investigations, incident response, divorce and other legal proceedings, employee misconduct investigations, counterterrorism efforts, fraud detection and data recovery.
Now let’s take a look at how digital forensic investigators assess the digital crime scene, search for clues, and piece together the story the data has to tell.
1. Collecting evidence
First, it’s time to get our hands on the evidence. This step involves identifying and gathering sources of digital evidence, as well as creating exact copies of information that could be linked to the incident. Indeed, it is important to avoid modifying the original data and, using appropriate tools and devicescreate their copies bit by bit.
Analysts are then able to recover deleted files or hidden disk partitions, ultimately generating an image equal in size to the disk. Labeled with the date, time and time zone, samples should be isolated in containers that protect them from the elements and prevent deliberate deterioration or alteration. Photos and notes documenting the physical condition of devices and their electronic components often help provide additional context and understanding of the conditions under which the evidence was collected.
Throughout the process, it is important to follow 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 to prevent corruption or falsification of data.
In accordance with the order of volatility, sample acquisition follows a systematic approach – from most volatile to least volatile. As also stated in the RFC3227 Following Internet Engineering Task Force (IETF) guidelines, the first step is to collect potential evidence, from data about memory and cache contents, to data on archival media.
2. Data retention
In order to lay the foundation for successful analysis, the information collected must be protected from damage and tampering. As stated previously, the actual analysis should never be carried out directly on the captured sample; rather, analysts must create forensic images (or exact copies or replicas) of the data on which the analysis will then be performed.
As such, this step revolves around a “chain of custody,” which is a meticulous record documenting the location and date of the sample, as well as the exact person who interacted with it. Analysts use hashing techniques to unequivocally identify files that could be useful to the investigation. By assigning unique identifiers to files via hashes, they create a digital fingerprint that makes it easier to trace and verify the authenticity of evidence.
In a nutshell, this step aims not only to protect the data collected but also, through the chain of custody, to establish a meticulous and transparent framework, while leveraging advanced hashing techniques to ensure the accuracy and reliability of the data. ‘analysis.
3. Analysis
Once the data has been collected and its preservation ensured, it is time to move on to the essentials and the real technological work of detective work. This is where specialized hardware and software come into play as investigators examine collected evidence to draw meaningful information 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, and the skill, domain-specific knowledge, and experience of the analyst.
Indeed, digital forensics requires a combination of technical skills, investigative acumen and attention to detail. Analysts must stay abreast of evolving technologies and cyber threats to remain effective in the fast-paced field of digital forensics. In addition, it is equally essential to be clear about what you are really looking for. Whether uncovering malicious activity, identifying cyberthreats or supporting prosecutions, the analysis and its results are based on well-defined investigative objectives.
Reviewing timelines and access logs is a common practice during this stage. This allows events to be reconstructed, action sequences established, and anomalies that may indicate malicious activity to be identified. For example, examining RAM is crucial to identify volatile data that might not be stored on disk. This may include active processes, encryption keys, and other volatile information relevant to the investigation.
4.Documents
All actions, artifacts, anomalies, and any patterns identified prior to this step should be documented in as much detail as possible. Indeed, the documentation must be sufficiently detailed so that another forensic expert can reproduce the analysis.
Documenting the methods and tools used throughout the investigation is crucial for transparency and reproducibility. This allows others to validate the results and understand the procedures followed. Investigators should also document the reasons for their decisions, especially if they encounter unexpected difficulties. This helps to justify the measures taken during the investigation.
In other words, meticulous documentation is not just a formality: it is a fundamental aspect of maintaining the credibility and reliability of the entire investigation process. Analysts must adhere to best practices to ensure their documentation is clear, complete, and complies with legal and forensic standards.
5. Reports
It is now time to summarize the results, processes and conclusions of the investigation. Often, an executive report is written first, describing key information clearly and concisely, without going into technical detail.
Then a second report called a “technical report” is established, detailing the analysis carried out, highlighting the techniques and the results, leaving aside the opinions.
As such, a typical digital forensics report:
- provides general information about the case,
- defines the scope of the investigation as well as its objectives and limits,
- describes the methods and techniques used,
- details the process of acquiring and preserving digital evidence,
- presents analysis results, including discovered artifacts, timelines, and patterns,
- summarizes the findings and their importance to the objectives of the investigation
Let us remember: the report must meet legal standards and requirements so that it can withstand legal scrutiny and serve as a crucial document in legal proceedings.
As technology becomes more and more integrated into various aspects of our lives, the importance of digital forensics in various fields is set to grow even further. Just as technology evolves, so do the methods and techniques used by malicious actors, always determined to obscure their activities or confuse digital sleuths. 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.