Understanding Digital Forensics: Process, Techniques, and Tools
What Is Digital Forensics?
Digital forensics is the practice of identifying, acquiring, and analyzing electronic evidence. Today almost all criminal activity has a digital forensics element, and digital forensics experts provide critical assistance to police investigations. Digital forensic data is commonly used in court proceedings.
An important part of digital forensics is the analysis of suspected cyberattacks, with the objective of identifying, mitigating, and eradicating cyber threats. This makes digital forensics a critical part of the incident response process. Digital forensics is also useful in the aftermath of an attack, to provide information required by auditors, legal teams, or law enforcement.
Electronic evidence can be gathered from a variety of sources, including computers, mobile devices, remote storage devices, internet of things (IoT) devices, and virtually any other computerized system.
Why Is Digital Forensics Important?
Digital forensics is commonly thought to be confined to digital and computing environments. But in fact, it has a much larger impact on society. Because computers and computerized devices are now used in every aspect of life, digital evidence has become critical to solving many types of crimes and legal issues, both in the digital and in the physical world.
All connected devices generate massive amounts of data. Many devices log all actions performed by their users, as well as autonomous activities performed by the device, such as network connections and data transfers. This includes cars, mobile phones, routers, personal computers, traffic lights, and many other devices in the private and public spheres.
Digital evidence can be used as evidence in investigation and legal proceedings for:
Data theft and network breaches—digital forensics is used to understand how a breach happened and who were the attackers.
Online fraud and identity theft—digital forensics is used to understand the impact of a breach on organizations and their customers.
Violent crimes like burglary, assault, and murder—digital forensics is used to capture digital evidence from mobile phones, cars, or other devices in the vicinity of the crime.
White collar crimes—digital forensics is used to collect evidence that can help identify and prosecute crimes like corporate fraud, embezzlement, and extortion.
In the context of an organization, digital forensics can be used to identify and investigate both cybersecurity incidents and physical security incidents. Most commonly, digital evidence is used as part of the incident response process, to detect that a breach occurred, identify the root cause and threat actors, eradicate the threat, and provide evidence for legal teams and law enforcement authorities.
To enable digital forensics, organizations must centrally manage logs and other digital evidence, ensure they retain it for a long enough period, and protect it from tampering, malicious access, or accidental loss.
Defining Digital Risks
As organizations use more complex, interconnected supply chains including multiple customers, partners, and software vendors, they expose digital assets to attack. Organizations also leverage complex IT environments including on-premise and mobile endpoints, cloud-based services, and cloud native technologies like containers—creating many new attack surfaces.
Digital risks can be broken down into the following categories:
Cybersecurity risk—an attack that aims to access sensitive information or systems and use them for malicious purposes, such as extortion or sabotage.
Compliance risk—a risk posed to an organization by the use of a technology in a regulated environment. For example, technologies can violate data privacy requirements, or might not have security controls required by a security standard.
Third party risks—these are risks associated with outsourcing to third-party vendors or service providers. For example, vulnerabilities involving intellectual property, data, operational, financial, customer information, or other sensitive information shared with third parties.
Identity risk—attacks aimed at stealing credentials or taking over accounts. These types of risks can face an organization’s own user accounts, or those it manages on behalf of its customers.
What Are the Different Branches of Digital Forensics?
Here is a brief overview of the main types of digital forensics:
Computer forensic science (computer forensics) investigates computers and digital storage evidence. It involves examining digital data to identify, preserve, recover, analyze and present facts and opinions on inspected information.
This branch of computer forensics uses similar principles and techniques to data recovery, but includes additional practices and guidelines that create a legal audit trail with a clear chain of custody.
Mobile Device Forensics
Mobile device forensics focuses primarily on recovering digital evidence from mobile devices. It involves investigating any device with internal memory and communication functionality, such as mobile phones, PDA devices, tablets, and GPS devices.
The network forensics field monitors, registers, and analyzes network activities. Network data is highly dynamic, even volatile, and once transmitted, it is gone. It means that network forensics is usually a proactive investigation process.
Forensic Data Analysis
Forensic data analysis (FDA) focuses on examining structured data, found in application systems and databases, in the context of financial crime. FDA aims to detect and analyze patterns of fraudulent activity.
Database forensics involves investigating access to databases and reporting changes made to the data. You can apply database forensics to various purposes. For example, you can use database forensics to identify database transactions that indicate fraud.
Alternatively, your database forensics analysis may focus on timestamps associated with the update time of a row in your relational database. This investigation aims to inspect and test the database for validity and verify the actions of a certain database user.
The Digital Forensics Process
The digital forensics process may change from one scenario to another, but it typically consists of four core steps—collection, examination, analysis, and reporting.
The collection phase involves acquiring digital evidence, usually by seizing physical assets, such as computers, hard drives, or phones. It is critical to ensure that data is not lost or damaged during the collection process. You can prevent data loss by copying storage media or creating images of the original.
The examination phase involves identifying and extracting data. You can split this phase into several steps—prepare, extract, and identify.
When preparing to extract data, you can decide whether to work on a live or dead system. For example, you can power up a laptop to work on it live or connect a hard drive to a lab computer.
During the identification step, you need to determine which pieces of data are relevant to the investigation. For example, warrants may restrict an investigation to specific pieces of data.
The analysis phase involves using collected data to prove or disprove a case built by the examiners. Here are key questions examiners need to answer for all relevant data items:
Who created the data
Who edited the data
How the data was created
When these activities occur
In addition to supplying the above information, examiners also determine how the information relates to the case.
The reporting phase involves synthesizing the data and analysis into a format that makes sense to laypeople. These reports are essential because they help convey the information so that all stakeholders can understand.
Digital Forensic Techniques
Digital forensics involves creating copies of a compromised device and then using various techniques and tools to examine the information. Digital forensics techniques help inspect unallocated disk space and hidden folders for copies of encrypted, damaged, or deleted files. Here are common techniques:
Cybercriminals use steganography to hide data inside digital files, messages, or data streams. Reverse steganography involves analyzing the data hashing found in a specific file. When inspected in a digital file or image, hidden information may not look suspicious. However, hidden information does change the underlying has or string of data representing the image.
Stochastic forensics helps analyze and reconstruct digital activity that does not generate digital artifacts. A digital artifact is an unintended alteration of data that occurs due to digital processes. Text files, for example, are digital artifacts that can content clues related to a digital crime like a data theft that changes file attributes. Stochastic forensics helps investigate data breaches resulting from insider threats, which may not leave behind digital artifacts.
Cross-drive analysis, also known as anomaly detection, helps find similarities to provide context for the investigation. These similarities serve as baselines to detect suspicious events. It typically involves correlating and cross-referencing information across multiple computer drives to find, analyze, and preserve any information relevant to the investigation.
Live analysis occurs in the operating system while the device or computer is running. It involves using system tools that find, analyze, and extract volatile data, typically stored in RAM or cache. Live analysis typically requires keeping the inspected computer in a forensic lab to maintain the chain of evidence properly.
Deleted File Recovery
Deleted file recovery, also known as data carving or file carving, is a technique that helps recover deleted files. It involves searching a computer system and memory for fragments of files that were partially deleted in one location while leaving traces elsewhere on the inspected machine.
Digital Forensic Tools
Before the availability of digital forensic tools, forensic investigators had to use existing system admin tools to extract evidence and perform live analysis. The drawback of this technique is that it risks modifying disk data, amounting to potential evidence tampering.
In 1989, the Federal Law Enforcement Training Center recognized the need and created SafeBack and IMDUMP. In 1991, a combined hardware/software solution called DIBS became commercially available. These tools work by creating exact copies of digital media for testing and investigation while retaining intact original disks for verification purposes.
By the late 1990s, growing demand for reliable digital evidence spurred the release of more sophisticated tools like FTK and EnCase, which allow analysts to investigate media copies without live analysis.
Today, the trend is for live memory forensics tools like WindowsSCOPE or specific tools supporting mobile operating systems. Commercial forensics platforms like CAINE and Encase offer multiple capabilities, and there is a dedicated Linux distribution for forensic analysis. Open source tools are also available, including Wireshark for packet sniffing and HashKeeper for accelerating database file investigation.
The main types of digital forensics tools include disk/data capture tools, file viewing tools, network and database forensics tools, and specialized analysis tools for file, registry, web, Email, and mobile device analysis.
When evaluating various digital forensics solutions, consider aspects such as:
Integration with and augmentation of existing forensics capabilities.
Support for various device types and file formats.
Availability of training to help staff use the product.
CLI, graphic UI, and ease of use.
Compatibility with additional integrations or plugins.
Types of configurations available.
Advanced features for more effective analysis.
Related content: Read our guide to digital forensics tools
DFIR: Combining Digital Forensics and Incident Response
Digital forensics and incident response (DFIR) is a cybersecurity field that merges digital forensics with incident response. DFIR aims to identify, investigate, and remediate cyberattacks. It helps reduce the scope of attacks and quickly return to normal operations.
DFIR involves using digital forensics techniques and tools to examine and analyze digital evidence to understand the scope of an event, and then applying incident response tools and techniques to detect, contain, and recover from attacks.
Here are key advantages of DFIR:
Proactive defense—DFIR can help protect against various types of threats, including endpoints, cloud risks, and remote work threats. It complements an overall cybersecurity strategy with proactive threat hunting capabilities powered by artificial intelligence (AI) and machine learning (ML).
Quick incident response—digital forensics provides your incident response process with the information needed to rapidly and accurately respond to threats. It can help reduce the scope of attacks, minimize data loss, prevent data theft, mitigate reputational damages, and quickly recover with limited disruption to your operations.
Consistent process—integrating digital forensics with incident response helps create a consistent process for your incident investigations and evaluation process. It helps obtain a comprehensive understanding of the threat landscape relevant to your case and strengthens your existing security procedures according to existing risks.
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