Digital forensics is the methodical securing, examination, analysis, and evaluation of digital data and traces. The goal is to reconstruct technical facts as transparently as possible and to capture relevant digital information in such a way that its origin, integrity, and investigative process can be documented. Digital forensics is used, among other things, with smartphones, computers, servers, hard drives, SSDs, USB drives, memory cards, emails, messenger data, cloud services, and IT systems.

This is not simply about opening existing files or recovering deleted data. A professional forensic investigation considers, even during the securing phase, how the digital evidence is handled, which changes are technically unavoidable or avoidable, and how each step is documented. The subsequent findings must be based on actual digital traces and clearly distinguished from assumptions or interpretations.

What exactly does digital forensics mean?

The term "digital forensics" refers to the systematic examination of digital data using forensic methods. The central question is what technically reliable findings can be obtained from a digital system or data storage medium. Depending on the investigation, it can be determined, for example, which files were present, when certain activities took place, which devices were connected, whether data was copied or deleted, or what communication and usage data is stored on a device.

Digital forensics therefore encompasses far more than simply searching for individual documents. A computer or smartphone contains a multitude of different data sources. In addition to the information directly visible to the user, operating systems, applications, and file systems can generate metadata, logs, databases, configuration information, timestamps, and other technical artifacts.

Only the analysis and correlation of such traces can make it possible to reconstruct events. Crucially, it is necessary to distinguish between a technically established fact, a conclusion derived from it, and a mere possibility.

What are the tasks of digital forensics?

A key initial task is to identify potentially relevant digital data and secure it professionally. The secured data is then examined using appropriate forensic methods. The methods required depend on the specific device, operating system, file system, security status, and the objective of the investigation.

Typical tasks may include reconstructing user activity, examining files and file systems, evaluating communication data, analyzing timestamps, identifying connected storage media, examining browser and application data, or searching for traces of a possible data leak.

Data recovery can also be part of an investigation. However, whether this is technically possible cannot be answered definitively. Modern encryption, flash memory, SSD TRIM, disk cleanup, overwriting, and the security mechanisms of current operating systems can significantly restrict or completely prevent recovery.

Which devices and data sources can be examined?

Digital forensics is not limited to traditional desktop computers. Virtually any electronic system that stores or processes data can potentially contain forensically relevant information.

• Windows PCs and notebooks
• Apple Mac and MacBook
• iPhones and iPads
• Android smartphones and tablets
• internal and external hard drives
• SSDs and NVMe storage
• USB sticks and memory cards
• Servers and virtual systems
• NAS and RAID systems
• Email mailboxes and email files
• Messenger and app data
• Cloud storage and cloud accounts
• Browser and internet data
• System, security, and application logs

Which of these sources may actually be examined and are technically accessible must be verified in each individual case. The mere fact that data would be technically accessible does not automatically mean that its collection or analysis is legally permissible.

How does a digital forensic investigation work?

The specific procedure depends on the subject of the investigation. Nevertheless, a professional investigation can generally be divided into several successive phases.

1. Investigation mandate and research question

The first step is to formulate a question as precisely as possible. For example, is the goal to determine whether company data was copied, whether a specific USB drive was connected, whether messages were present, or whether there are indications of unauthorized access? A clearly defined question prevents an unnecessarily broad investigation and facilitates the subsequent evaluation of the results.

2. Identification and securing of digital evidence

Relevant devices and data sources are identified and their initial state documented. Depending on the system, a forensic copy or image can then be created. For suitable storage media, hardware or software mechanisms can be used to prevent or minimize write access to the original.

With modern smartphones, encrypted systems, and running IT systems, a completely write-free backup is not technically possible in every situation. Therefore, professional forensics does not mean claiming blanket freedom from alteration. The crucial point is to identify unavoidable changes, limit them to the necessary extent, and document them in a traceable manner.

3. Integrity check

Cryptographic hash values ​​are frequently used in forensic imaging. A hash value is a verification value calculated from the data. If the hash values ​​of a secured dataset match during subsequent checks, it can be technically verified that this dataset has not been altered since its calculation.

However, a hash value does not automatically answer all questions about the origin or authenticity of content. It primarily proves the consistency of the hashed data sets. This distinction is essential for the proper evaluation of digital evidence.

4. Forensic Analysis

The actual investigation is always conducted on a sound basis, insofar as the technical procedure allows. Forensic software can structure large amounts of data, interpret file systems, analyze databases, process timestamps, and recognize known artifacts from various operating systems and applications.

Software does not replace expert evaluation. A data set displayed by the analysis program must be interpreted within the context of its source, its data format, and the respective technical environment. Misinterpretations, especially with timestamps, deleted data sets, and automatically generated system information, can lead to incorrect conclusions.

5. Correlation and Reconstruction

Individual digital traces often have limited significance. A combination of several independent data sources can be more informative. For example, file system information, USB artifacts, user activity, and application data can together provide clues about a specific sequence of events.

A reliable reconstruction should therefore not be hastily derived from a single artifact. Contradictory evidence must be considered, as well as information that does not confirm an initially plausible hypothesis.

6. Documentation and evaluation

The results are documented in a transparent and comprehensible manner. Depending on the assignment, this includes the evidence examined, the methods used for securing evidence, the procedures employed, the relevant findings, and their technical evaluation. It is equally important to disclose any existing limitations and uncertainties.

Professional forensic documentation should clearly indicate the data on which a statement is based. Findings and interpretations must not be conflated.

What is forensic data backup?

A forensic data backup differs from a regular file copy. A normal copy typically only transfers selected files. Depending on the backup method, a forensic image, on the other hand, can contain a much more comprehensive representation of a data carrier.

With traditional storage media, this can mean capturing the addressable data carrier sector by sector or bit by bit. Under certain conditions, this allows not only regular files but also file system structures and other storage areas to be preserved for later analysis.

Smartphones and modern closed systems have different technical requirements. Depending on the device and access options, different extraction methods are used. The terms logical, file system, or physical extraction describe different levels of access and should not be used interchangeably.

What are digital traces?

Digital traces are pieces of information that are created or modified through the use of a device, application, or IT system. Many of these traces are not consciously created by the user. Operating systems and applications continuously generate technical information in the background.

This can include file timestamps, logs, database entries, browser information, connection data, app artifacts, device information, login data, Wi-Fi information, or indications of connected USB devices. Which traces are actually present depends heavily on the specific system and its configuration.

Therefore, an important principle is: The absence of a particular artifact does not automatically prove that an action did not take place. Likewise, the presence of an artifact does not, without further examination, prove all conceivable accompanying circumstances of an action.

What is the significance of timestamps?

Timestamps are among the most important, but also most error-prone, sources of information in digital forensics. Files, operating systems, databases, and applications can store various timestamps. These include, for example, creation, modification, access, or internal event times.

These values ​​must be interpreted within the context of the respective system. Time zones, daylight saving time, synchronization mechanisms, copying processes, software behavior, or deliberate manipulation can all influence time readings. Therefore, an isolated time reading should not be considered irrefutable proof of a specific user action without further verification.

When creating an event timeline, multiple data sources should be compared whenever possible. The better the various independent artifacts align chronologically, the more reliable the reconstruction can be.

Can deleted data be recovered?

Technically, "deleted" doesn't always mean that the original data is immediately and completely removed from the storage medium. With some file systems, only the file association is removed initially, and the corresponding storage area is freed up for reuse.

Whether data can still be recovered afterwards depends on numerous factors. Crucial among these are the storage type, file system, encryption, time of deletion, subsequent device usage, and possible overwriting processes.

With modern SSDs and flash storage devices, mechanisms like TRIM and garbage collection can significantly change the situation. Current smartphones also employ extensive hardware- and software-based encryption. Therefore, the blanket statement that deleted data can always be recovered would be technically incorrect.

What role does encryption play?

Encryption is one of the central challenges of modern digital forensics. Current smartphones, computers, and cloud services often employ strong cryptographic protection mechanisms. Without the necessary access credentials or technically suitable access, data may be unavailable or only partially available for investigation.

The assessment also requires distinguishing between different system states. A running and already unlocked device may, under certain circumstances, offer different access options than a switched-off or locked device. The specific options available depend on the hardware, operating system version, security status, and other technical factors.

Digital forensics on smartphones

Mobile forensics is a distinct subfield of digital forensics. Smartphones contain a particularly high density of personal and communication-related data. Depending on the device and extraction method, contacts, call data, messages, photos, videos, app data, browser information, and other system artifacts may be available for investigation.

Technological developments in this area are progressing very rapidly. Manufacturers are constantly changing security architectures, encryption methods, and operating systems. Therefore, what data can be obtained from a specific smartphone must be examined based on the concrete model, the operating system version, and the device's condition.

Digital forensics for computers and notebooks

For Windows PCs and Macs, the focus is often on file systems, user activity, external storage media, browser data, emails, programs, and system logs. In corporate settings, for example, it can be investigated whether specific files have been opened, modified, deleted, or transferred to external storage devices.

Here too, it's important to consider individual artifacts within their technical context. For example, the existence of a file on a system doesn't automatically prove which user deliberately placed it there. A thorough evaluation therefore considers as many leads and alternative explanations as possible.

Digital forensics in cases of suspected data theft

A typical reason for an investigation in companies is the suspicion that current or former employees have copied or passed on confidential data. Such questions can arise particularly before dismissals, job changes, or corporate disputes.

Depending on the system, evidence of connected USB storage devices, external hard drives, cloud services, email activity, file access, or copying operations can be examined. Whether this actually proves a data breach depends on the available evidence.

Especially in such cases, securing evidence early is advisable. Continued use of a computer can alter or overwrite relevant system information.

Digital forensics after a cyberattack

Following an IT security incident, digital forensics can be used to investigate the course of an attack. Possible questions include the original access path, compromised user accounts, malware, system changes, or potential data leaks.

This can involve analyzing event logs, network and firewall data, email information, file system artifacts, and other technical sources. In complex incidents, digital forensics and incident response overlap. While the immediate response to an ongoing security incident primarily focuses on containment and restoring operations, forensic investigations concentrate more on securing, reconstructing, and technically evaluating the evidence.

What is the significance of forensic tools?

Professional digital forensics uses specialized hardware and software for data backup, extraction, processing, and analysis. Different tools may be required depending on the task. No single program covers all devices, operating systems, file systems, and forensic issues equally well.

Tools can extract data and automatically interpret artifacts. However, the professional responsibility for the evaluation remains with the investigator. Particularly relevant findings should be validated, if necessary, using their original data source or an independent method.

What distinguishes digital forensics from a normal IT analysis?

In a typical IT analysis, the focus is often on troubleshooting. The goal is to get a system up and running again as quickly as possible. This can involve changing configurations, installing programs, moving files, or restarting systems.

In a forensic investigation, precisely such changes can be problematic because they affect existing evidence. Therefore, the primary focus is on the controlled preservation and documentation of the initial state. The analysis should be performed on a suitable backup or working copy wherever technically feasible.

This does not mean that no changes whatsoever may occur during any forensic investigation. Especially with mobile devices or live systems, access can cause technically induced changes. The crucial factor is a methodically controlled and documented approach to handling such changes.

When can digital forensics be useful?

A forensic investigation may be considered whenever a matter needs to be objectively verified or reconstructed using digital data. This applies to companies and lawyers as well as private individuals and other clients.

• Suspected data theft or data leak
• Unauthorized copying or deletion of company data
• Suspected unauthorized access to user accounts or devices
• Examination of smartphones and computers
• Reconstruction of digital communication
• Examination of emails and messenger data
• Analysis of IT security incidents
• Search for technically available deleted data
• Reconstruction of user activities
• Securing digital data for legal disputes

What are the limits of digital forensics?

Digital forensics can only work with traces that exist, are accessible, and can be technically interpreted. It cannot reconstruct data that is no longer present. Likewise, a technical examination cannot automatically prove human intent.

For example, a file may demonstrably have been transferred to a storage medium. This does not automatically imply who deliberately initiated the process or what their motivation was. Such further conclusions require additional evidence or an assessment beyond purely technical findings.

Modern encryption, damaged storage media, missing access data, overwritten data, and limited logging can also restrict the investigation. Reputable digital forensics explicitly states these limitations instead of feigning a lack of evidentiary certainty.

Why is the chain of evidence important?

The so-called chain of custody documents the handling of digital evidence. This can include when and by whom a device was taken over, how it was labeled and stored, when a backup was performed, and on what basis subsequent work was carried out.

A traceable chain of evidence makes it easier to later verify whether the examined data can be attributed to the originally acquired evidence and how it was handled during the investigation.

What is the significance of a forensic report?

A technical investigation and a forensic report are not the same. An investigation first generates findings and analytical data. A report evaluates these results in relation to a specific question and explains, in a comprehensible manner, what conclusions can be drawn from the examined data.

A good expert report should not only state the result. It should clearly identify which data were examined, which methods were used, on which technical traces the findings are based, and what limitations exist. Especially in complex cases, the distinction between findings and evaluation is essential.

What should be considered regarding potential digital evidence?

If there is a suspicion that a smartphone, computer, or storage device will later need to be forensically examined, the device should not be used unnecessarily. Any further use can generate new data, alter logs, and overwrite released storage areas.

Attempts to delete data independently, the installation of purported analysis or recovery programs, and uncontrolled modifications to the system can further complicate subsequent investigations. Therefore, when dealing with important evidence, it is crucial to determine early on how the system in question can be properly secured.

Frequently asked questions about digital forensics

Can digital forensics make deleted data visible?

Yes, under certain technical conditions. Whether recovery is possible depends on factors such as the storage medium, file system, encryption, overwriting, and further use of the device. Therefore, recovery can never be guaranteed in general.

Is it possible to determine if files have been copied?

In certain situations, technical traces can provide clues to copying operations or the use of external storage media. Whether a specific copying operation can be definitively proven depends on the existing artifacts and the systems involved.

Can a deleted WhatsApp chat be recovered?

This depends on factors such as the smartphone, operating system, deletion time, existing backups, continued use, and available extraction methods. Modern encrypted smartphones have significant technical limitations. Therefore, a general guarantee would be irresponsible.

Can a smartphone be completely read?

Not necessarily. The amount of available data depends on the model, operating system version, security status, encryption, access options, and the extraction method used. Different extraction methods can yield significantly different amounts of data.

Does a forensic examination change the device?

With traditional storage media, backups can be write-protected under suitable conditions. However, with smartphones and running systems, technically induced changes cannot always be completely ruled out. These should be minimized and documented.

Is a screenshot considered digital evidence?

A screenshot can be relevant to a situation, but on its own it has limited technical significance. It primarily shows a visual representation. For questions about origin, completeness, authenticity, or context, the original data and further technical information can be significantly more informative.

How long does a digital forensic investigation take?

This cannot be determined in general terms. Data volume, number of devices, encryption, condition of the data carriers, complexity of the question, and scope of the required analysis significantly influence the time required.

Can digital forensics prove who carried out an action?

Digital traces can, under certain conditions, be linked to a user ID, a device, an account, or a specific transaction. However, definitively determining which natural person actually performed an action is not always possible based solely on technical data.

Digital forensics as a verifiable technical investigation

The value of digital forensics does not lie in the largest possible data sets or in the mere use of powerful software. What is crucial is whether methodically verifiable findings can be derived from digital traces.

A professional investigation therefore begins with the acquisition and securing of the evidence. It takes into account the technical characteristics of the system under investigation, documents the investigation process, and distinguishes findings from interpretations. Where the data does not allow for a clear conclusion, this limitation must also be stated.

Understood in this way, digital forensics is the structured technical reconstruction of digital facts based on actually existing and verifiable data.