Digital forensics refers to the recovery and investigation of material found in digital devices that may be evidence of crimes. As society becomes more and more reliant on computer systems, digital forensics has become a critical facet for law enforcement agencies and businesses globally.
This post will discuss everything you need to know when it comes to digital forensics.
What is digital forensics?
When someone commits a crime, investigators rely on evidence to prove their guilt. Traditional forensics involves the use of scientific methods to extract and process this evidence. These methods may include pulling fingerprints off of items and checking them against records, collecting blood samples, analyzing ballistic patterns, and so on.
With the invention and proliferation of computers and digital devices that collect and store data, these devices became another place where evidence of crimes could be found. Sometimes, that evidence is simply email exchanges or data files that contain evidence of a robbery, assault, or financial crime. Other times, it is evidence of a cybercrime, such as when someone hacks into a system to steal or ransom data. The forensic investigator would then be responsible for determining how the attacker gained access, what they stole, and anything that might point to their location or identity.
In general, digital forensics is a branch of forensics that focuses on finding, preserving, documenting, and analyzing any criminal evidence stored on digital devices. This evidence may be in the form of documents, photos, emails, event records, or system logs, and it may be stored on computers, cellphones, in the cloud, on hard drives, or flash drives. Frequently, the evidence may have been deleted or tampered with, which means investigators must use various methods to recover the original data once it is identified.
What is the purpose of digital forensics?
Often, the goal of digital forensics is to collect and extract evidence of crimes involving digital devices so that it may be presented and used in a court of law. Criminals can only be convicted and punished for their crimes if those crimes can be proven beyond a reasonable doubt. When that’s the case, this evidence is held to high standards and must meet certain regulations related to how it was acquired and how it exchanged hands — just as with any evidence collected for legal cases.
Sometimes, however, digital forensics in a criminal case is more focused on intelligence gathering — determining if a crime will be committed or working to halt it. In such cases, there is a less strict standard because the intelligence isn’t being used to directly convict someone of a crime.
Digital forensics investigations may also be conducted privately for internal purposes — such as when a company needs to determine if an employee has been undermining operations from within before laying them off. It may also be used by IT and security professionals to identify weaknesses or the source of a recent hack.
Phases of digital forensics
The process of a digital forensics investigation follows four basic phases. First, the devices which contain the evidence must be found and secured. Then, the evidence itself must be identified and extracted from those devices. That evidence is then processed or analyzed before being documented and reported.
1. Search and seizure
If the evidence is to be used for a criminal case, law enforcement is often brought in to collect any suspect digital devices. This is usually part of the execution of a search warrant, or it may take place during an arrest. The individuals responsible for finding and collecting the digital devices in question are responsible for ensuring that collection is done in accordance with legal standards and that any evidence they contain is properly preserved.
If the search and seizure is part of a civil case or an internal investigation, then the legal assumption is that companies are allowed to collect and investigate their own equipment as long as human rights and employee privacy are maintained in the process.
2. Data acquisition
Once the devices have been seized, forensic investigators then use specialized methods to extract evidence from those devices. When it comes to criminal cases, this must be done in accordance with all rules and regulations associated with evidence handling, which is why it is important that digital forensic scientists are properly trained for this work.
Data acquisition must be done in a safe environment where any extracted evidence can be secured. The investigators are also responsible for ensuring that the data collected is accurate and authentic. Improper processes can alter the data and damage its integrity. This is why the data on any seized devices is typically duplicated first via a process called imaging. That way, the original can always be referred to again if there are any questions, and everyone can rest assured that it remains in its original state even as the copy is dissected and analyzed.
3. Data analysis
The real meat of digital forensics happens in the data analysis phase. This is where the actual evidence is separated from the rest of the acquired data and converted or modeled so that it illustrates useful information that can be used in court. The evidence may be in files or documents themselves, or it may be in the event logs — as would be the case if the investigation is looking for evidence of tampering or deleted files.
Forensic scientists use a variety of tools and methods to examine and analyze the acquired data. These tools and methods help with both viewing and recovery of data that may be stored in emails, chat logs, internet history, cache files, or a number of other locations. During the data analysis process, the media is often re-verified several times through a process called hashing, which ensures that it has not been modified or tampered with.
4. Documentation and reporting
After all of the evidence is uncovered, it can then be used to put together the larger picture of what happened, who is responsible, and how the criminal activity played out. This happens in the final phase of documentation and reporting.
Generating the final report requires translating highly technical concepts or findings into a form easily digestible to a non-technical audience. These reports may be handed off to law enforcement who will use them to further their investigation, or they may be presented as evidence in a court of law. When used in court, the report may include an expert summary and conclusion or require accompanying expert testimony so that the results may be explained in detail and cross-examined.
If the report is the result of a private or internal investigation, then it most likely is destined for internal eyes only and may be used to make personnel decisions or to inform cybersecurity practices moving forward.
History of digital forensics
The history of digital forensics unsurprisingly follows the history of computing. The ability to share data between computers and the first computers designed for home use appeared in the 1970s. And it was in 1978 that computer crimes were first recognized by the Florida Computer Crimes Act. This act detailed legislation prohibiting unauthorized modification or deletion of data on computer systems.
Computer crime laws really took off in the 1980s and 90s as computer crimes began ramping up. The FBI’s Computer Analysis and Response Team formed in 1984, and many similar entities followed. Initially, techniques and tools were largely ad-hoc. In 1992, the phrase “computer forensics” first appeared in an official context in an academic paper, and soon an official discipline was formed.
However, it wasn’t until the 2000s that standards around the seizure, collection, analysis, and use of digital evidence emerged. Various organizations then began formalizing sets of guidelines, procedures, and best practices. In an attempt to reconcile national computer crime laws and techniques, a 2004 Convention on Cybercrime treaty was signed by 43 nations, including the United States. Soon after, organizations developed training and certification programs for digital forensics.
As technology evolves, so does the field of digital forensics. In recent years, many sophisticated tools and techniques for use in digital forensic investigations have emerged, both for use on computers as well as cellphones and other electronic devices that can store data.
Different branches of digital forensics
Because electronic devices are so prolific and varied, modern digital forensics now contains subspecialties, each focused on different types of data or places where data is stored.
Computer forensics
The most fundamental branch of digital forensics focuses on where the entire field got its start — the computer. This branch covers the extraction of any evidence found on computers or other digital storage media. Computer forensics relies on many of the same tools and techniques that are used in the field of data recovery, but forensics additionally requires adherence to legal guidelines and the creation of an audit trail.
Computer forensics can help extract and preserve evidence associated with cybercrimes like hacking or ransomware, or other crimes such as child pornography, fraud, espionage, and even murder. It may be as simple as information retrieval, or it can involve searching event logs, recovering deleted files, and piecing together multiple items that form the larger story of a sophisticated crime.
Memory forensics
The field of memory forensics focuses more specifically on analyzing whatever is stored in a device’s digital memory. Most often, this specialization is used for investigating cyberattacks by looking for evidence that may have been left on a computer’s hard drive or RAM. While initially an ad-hoc specialty reliant on generic data analysis tools, modern memory forensics includes a number of advanced and more practical toolkits, some of which are open source.
Memory forensics can look into volatile or temporarily stored runtime data that otherwise disappears when a computer is powered off. Often this is the only place where data pertaining to cyberthreats resides. With the complexity and sophistication of cyberattacks continuously on the rise, memory forensics is vital in staying one step ahead or uncovering a culprit’s tracks.
Network forensics
Network forensics is used both for network security to identify anomalous traffic or intrusion attempts and for legal cases that may rely on evidence related to transferred files or communication. The subspecialty of network forensics looks at both local and wide area network traffic. Because network traffic data is not often logged, data acquisition in network forensics typically occurs in real-time, usually by intercepting data at the packet level. This is why network forensics is often concerned with monitoring just as much as it is concerned with analysis; it is more proactive by nature.
Network data collection occurs in one of two ways. The first way is by capturing and writing to store all packets that pass through a certain point for later analysis. The second method involves performing a real-time rudimentary analysis of each packet and retaining only a subset of information for future analysis.
Database forensics
Database forensics focuses on databases and associated metadata. It may also involve looking into RAM caches using live analysis techniques. Investigators may look at things like update timestamps or trace the actions and edits of a particular user that follow a pattern of wrongdoing. Many software tools exist that can help manipulate and analyze database data in a way that keeps an audit log for legal purposes.
Mobile device forensics
Because the little computers people carry around in their pockets often contain invaluable data when it comes to both regular and cybercrimes, there is also a specialization that focuses on mobile device forensics. Mobile devices are different from standard computers because they come with inbuilt communication systems and often have proprietary storage mechanisms.
Useful evidence pulled from mobile devices may include phone call histories, text messages, or even location data history — which could place a suspect at the location and time of a crime or support their alibi. Mobile devices may be used in cybercrimes or crimes related to online transactions, or they may contain location and communication records of someone committing a robbery, murder, or other criminal act.
How robust is your security?
Digital forensics has applications in both legal situations and for situations involving internal investigations for cybercrimes and security. If you wish to collect and analyze digital evidence for legal proceedings, you must make sure you are adhering to all associated laws and regulations. And when it comes to cybercrimes, the better your digital forensics solution, the better your ability to respond, defend against, and mitigate cyberattacks.
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