Introduction to Digital Forensics with Python
Introduction to Digital Forensics with Python
This chapter will introduce you to digital forensics and its historical perspective. You will also learn about real-life applications of digital forensics and its limitations.
What is Digital Forensics
Digital forensics can be defined as a branch of forensic science that analyzes, examines, identifies, and recovers digital evidence residing on electronic devices. It is commonly used in criminal law and private investigations.
For example, if someone steals data from an electronic device, you can rely on digital forensics techniques to extract evidence.
A Brief Historical Review of Digital Forensics
This section explains the history of computer crime and the historical perspective of digital forensics, as follows.
1970s-1980s: The First Computer Crimes
Before this decade, no one recognized computer crimes. However, if they were to occur, the laws of the time would have dealt with them. Later, in 1978, Florida’s Computer Crime Act recognized computer crimes for the first time, including legislation targeting the unauthorized modification or deletion of data on computer systems. However, over time, the scope of computer crime expanded due to technological advances. Various other laws were also passed to address crimes related to copyright, privacy, and child pornography.
1980s–1990s: A Decade of Development
This decade marked the development of digital forensics, fueled by the first-ever investigation (1986) in which Cliff Stoll tracked down a hacker named Markus Hess. During this period, two digital forensics disciplines developed—the first, based on ad hoc tools and techniques developed by practitioners as a hobby, and the second, developed by the scientific community. In 1992, the term “computer forensics” was coined in academic literature.
2000s-2010s: The Decade of Standardization
Once digital forensics had reached a certain level of development, specific standards needed to be established to guide investigations. Consequently, various scientific institutions and groups published guidelines for digital forensics. In 2002, the Scientific Working Group on Digital Evidence (SWGDE) published a paper titled “Best Practices in Computer Forensics.” Another highlight was the European-led international treaty, the Cybercrime Convention, signed by 43 countries and ratified by 16. Even with these standards, some issues identified by researchers still needed to be addressed.
The Digital Forensics Process
Since the first computer crimes emerged in 1978, digital criminal activity has grown tremendously. This growth necessitated a structured approach to addressing them. A formalized process was introduced in 1984, and since then, numerous new and improved computer forensic investigation procedures have been developed.
A computer forensics investigation process consists of three main phases, explained below.
Phase I: Acquiring or Imaging Evidence
The first phase of digital forensics involves preserving the state of a digital system for later analysis. This is very similar to taking photographs, blood samples, etc. from a crime scene. For example, it involves capturing images of allocated and unallocated areas of a hard drive or memory.
Phase II: Analysis
The input to this phase is the data obtained during the acquisition phase. Here, this data is examined to determine the evidence. This phase presents the following three types of evidence.
- Evidence of Innocence – This is evidence that supports a particular history.
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Evidence of Exculpation – This is evidence that contradicts the given history.
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Evidence of Tampering – This is evidence that the system has been tampered with to avoid identification. This involves examining file and directory contents to recover deleted files.
Phase 3: Presentation or Reporting
As the name suggests, this phase presents the findings and corresponding evidence from the investigation.
Applications of Digital Forensics
Digital forensics involves collecting, analyzing, and preserving evidence from any digital device. The use of digital forensics depends on the application. As mentioned previously, it is primarily used in two situations:
Criminal Law
In criminal law, evidence is collected to support or disprove a hypothesis in court. The forensic process is very similar to that used in criminal investigations, but with different legal requirements and restrictions.
Private Investigations
Digital forensics is primarily used in private investigations within the corporate world. This method is used when a company suspects that an employee may be engaging in illegal activity on their computer that violates company policy. Digital forensics offers one of the best avenues for companies or individuals investigating digital misconduct.
Digital Forensics Branches
Digital crime isn’t limited to computers; hackers and criminals are also using small digital devices, such as tablets and smartphones, on a large scale. Some devices have volatile memory, while others have non-volatile memory. Therefore, digital forensics has several branches, depending on the type of device.
Computer Forensics
This branch of digital forensics involves computers, embedded systems, and static storage devices, such as USB drives. Computer forensics can investigate a wide range of information, from logs to the actual files on the drive.
Mobile Forensics
This branch involves investigating data on mobile devices. This branch differs from computer forensics because mobile devices have built-in communication systems that can provide useful location-related information.
Network Forensics
This branch involves monitoring and analyzing computer network traffic, including local and WAN (wide area network) traffic, for information gathering, evidence collection, or intrusion detection.
Database Forensics
This branch of digital forensics involves the forensic study of databases and their metadata.
Skills Required for Digital Forensic Investigations
Digital forensic examiners help track hackers, recover stolen data, trace the source of computer attacks, and assist in other types of investigations involving computers. Some key skills required to become a digital forensic examiner are described below.
Excellent Thinking Skills
A digital forensic investigator must be an excellent thinker and should be able to apply different tools and methods to a specific task to achieve results. He or she must be able to find different patterns and draw connections between them.
Technical Skills
A digital forensic examiner must have good technical skills, as this field requires knowledge of networks and how digital systems interact.
Passion for Cybersecurity
Because the field of digital forensics is all about solving cybercrimes, a tedious task, it takes a great deal of passion to become an ace digital forensics investigator.
Communication Skills
Excellent communication skills are essential to coordinate different teams and extract any missing data or information.
Proficient Reporting
After successfully completing acquisition and analysis, the digital forensic examiner must address all findings in the final report and presentation. Therefore, they must possess excellent reporting skills and attention to detail.
Limitations
Digital forensic investigations have certain limitations, which are discussed here.
Requirement to Provide Convincing Evidence
One of the major drawbacks of digital forensics investigations is that the examiner must adhere to the standards required for court evidence, as data can be easily tampered with. On the other hand, computer forensic investigators must have a thorough understanding of legal requirements, evidence handling, and documentation procedures in order to present convincing evidence in court.
Investigative Tools
The effectiveness of a digital investigation depends entirely on the digital forensic examiner’s expertise and selection of appropriate investigative tools. If the tools used do not meet the required standards, the evidence will be rejected by the judge in court.
Lack of Technical Knowledge among the Audience
Another limitation is that some people are not fully familiar with computer forensics; therefore, many are unaware of this field. Investigators must ensure that their findings are communicated to the court in a manner that helps everyone understand the results.
Cost
The cost of producing and preserving digital evidence is very high. Therefore, many people may not choose this process because they cannot afford it.