What is Digital Forensics?

When a cyberattack hits a business or an employee is suspected of stealing data, the immediate question is: what actually happened? Which systems were affected? What was taken? Who was responsible, and when did it start?

Answering those questions accurately, and in a way that holds up legally, is what digital forensics does.

If you are reading this because a cyber incident is happening right now and you do not know what to do, contact Zensec immediately.

What is digital forensics?

Digital forensics is the process of uncovering, preserving, and analysing digital evidence for use in legal proceedings or internal investigations. It is the discipline that enables organisations and law enforcement agencies to reconstruct events on a computer system, network, or mobile device after a cyber incident, data breach, or suspected criminal activity.

The goal is not simply to find evidence. It is to find evidence in a legally sound way: collected without alteration, documented with a clear chain of custody, and presented in a form that is admissible in court if required. Digital evidence is extremely volatile. Careless handling can destroy it entirely, or render it inadmissible.

As the NCSC’s caseload continues to grow sharply, reaching 204 nationally significant cyber attacks against the UK in the twelve months to August 2025, up from 89 the year before, the importance of digital forensics to both law enforcement and to private organisations has never been greater.

The branches of digital forensics

Digital forensics covers several distinct areas, and a serious investigation will often require expertise across more than one of them.

Computer forensics

Computer forensics focuses on personal computers, laptops, and servers. It examines storage media such as hard disks and solid-state drives to recover files, including deleted files, and reconstruct user activity. If a computer was left running when it was seized, memory forensics can recover volatile data from RAM, capturing information about what the user was doing in the moments before the machine was shut down. Volatile data disappears when a device loses power, so securing it is a time-critical step.

Network forensics

Network forensics examines traffic flowing across a computer network. When a threat actor is present in an organisation’s environment, the network often contains evidence of their activities: communications with command-and-control infrastructure, exfiltrated data, or lateral movement between systems. Network data analysis can establish not just that an intrusion occurred, but how the attacker moved, what they accessed, and when.

Mobile device forensics

Mobile devices have become one of the most consequential areas of digital forensic investigation. Mobile devices carry call histories, messages, application data, location information, and records of connected devices. The challenge is that mobile devices are highly diverse, and the extraction process must be handled precisely, since a mistake can compromise the evidence or, in the worst case, make it inadmissible.

Cloud forensics

This form of forensics addresses the growing volume of data held in cloud environments such as AWS and Microsoft Azure. Investigating these environments requires specialist knowledge of how cloud platforms log activity, retain data, and provide access to forensic images, as the approaches used for physical hardware do not directly transfer.

File system forensics and database forensics round out the picture, covering the structure and contents of file systems and the records held within databases, often essential when investigating data theft or unauthorised access to sensitive information.

The digital forensics process

Whatever the environment being investigated, digital forensic investigations follow a consistent process.

The first phase is identification: determining what digital devices, systems, and data sources are relevant to the investigation. This includes connected devices, cloud accounts, email systems, and any storage media used to exfiltrate data.

The second phase is preservation: creating forensic images of the relevant devices and data before any analysis begins. Working from copies rather than originals ensures that the original evidence is not altered during the investigation. This is not a bureaucratic formality; it is the foundation on which the legal credibility of every subsequent finding rests.

The third phase is analysis: using digital forensic tools to examine the collected data, recover deleted files, reconstruct timelines, and identify the digital traces left by the activity under investigation. Specialist tools are used at this stage, including software for analysing hard disks and memory, as well as tools designed specifically for mobile device analysis. Forensic analysts typically use multiple tools to validate findings.

The fourth phase is presentation: documenting forensic findings in a report understandable to legal teams, senior management, or a court. The report must not only explain what was found but demonstrate how it was found and why the process used was sound.

Chain of custody and data collection

The chain of custody is the documented record of every person who has handled the evidence, and every action taken on it, from the moment of collection through to presentation. It exists to prove that the evidence has not been tampered with or altered.

If the chain of custody is broken or cannot be demonstrated, the technical evidence may be inadmissible in criminal investigations or civil legal proceedings. This is why digital forensic investigators follow strict protocols for evidence collection and documentation, and why the involvement of qualified forensic professionals from the outset of an investigation matters so much.

Common digital forensics tools

Specialist software can help security teams and analysts collect, preserve, and understand digital evidence without altering the original data.

Digital forensic investigators use specialist software to collect, preserve, and analyse digital evidence without altering the original data. There are multiple tools available, including:

• Disk Imaging and Computer Forensics Tools: These tools create forensic copies of storage devices and recover deleted or hidden files. EnCase and FTK are popular options for law enforcement and in corporate investigations, due to their ability to maintain evidential integrity.
• Memory Forensics Tools: Frameworks such as Volatility can identify active processes, network connections, malware activity, and evidence that may never be written to disk. Memory forensics tools can support advanced ransomware and intrusion investigations.
• Network Forensics: Network forensic investigations use packet analysis and traffic monitoring tools. Platforms like Wireshark let digital forensics investigators inspect network traffic in detail, identify suspicious communications, and assess how attackers move between systems.
• Mobile Device Forensics: Modern smartphones are complex, and forensics investigations require specialised tools. Options such as Cellebrite extract digital data, including call logs, messages, application data, media files, and location information.
• Open-Source Forensics Tools: Platforms such as Autopsy are beneficial for forensic examination, file analysis and timeline reconstruction.

Important: No single tool catches each type of evidence perfectly. Experienced investigators use multiple tools for accuracy and validation.

Digital forensics in a business context

Digital forensics is often associated with law enforcement and criminal cases, but it plays an equally important role in the corporate environment.

When a data breach occurs, a digital forensic investigation establishes what data was accessed, how the attacker gained entry, how long they were present, and what they took. That analysis directly informs the organisation’s legal obligations, including what must be reported to the ICO under UK GDPR.

Insider threats are another significant driver. When an employee is suspected of data theft, leaking sensitive data, or improperly using company systems, digital forensics can recover the electronic evidence needed to support disciplinary action or legal proceedings. The digital footprint left on corporate systems, email accounts, and devices is often more complete than people expect.

Identity theft, fraud, and intellectual property theft all generate digital evidence that a properly conducted investigation can uncover. In each of these cases, the value of acting quickly cannot be overstated: the longer the gap between an incident and the start of an investigation, the more evidence may be lost.

For organisations that want the capability to respond effectively when an incident occurs, Zensec’s digital forensics and incident response service provides the expertise to collect, preserve, and analyse digital evidence to the standard required for legal proceedings, while simultaneously supporting recovery.

Why digital forensics matters in today’s digital world

Every device, system, and cloud service used in a modern organisation generates records of what happened, who accessed what, and when. Digital information is valuable in two ways: attackers can exploit it, and defenders can use it to reconstruct events after an incident.

Understanding digital forensics matters not just to investigators but also to the organisations that will rely on their findings. The earlier forensic professionals are engaged after a suspected incident, the better the quality of the evidence they can recover, and the stronger the organisation’s position is when it matters most.