This chapter will give you an introduction to what digital forensics is all about, and its historical review. You will also understand where you can apply digital forensics in real life and its limitations.
Digital forensics may be defined as the branch of forensic science that analyzes, examines, identifies and recovers the digital evidences residing on electronic devices. It is commonly used for criminal law and private investigations.
For example, you can rely on digital forensics extract evidences in case somebody steals some data on an electronic device.
The history of computer crimes and the historical review of digital forensics is explained in this section as given below −
Prior to this decade, no computer crime has been recognized. However, if it is supposed to happen, the then existing laws dealt with them. Later, in 1978 the first computer crime was recognized in Florida Computer Crime Act, which included legislation against unauthorized modification or deletion of data on a computer system. But over the time, due to the advancement of technology, the range of computer crimes being committed also increased. To deal with crimes related to copyright, privacy and child pornography, various other laws were passed.
This decade was the development decade for digital forensics, all because of the first ever investigation (1986) in which Cliff Stoll tracked the hacker named Markus Hess. During this period, two kind of digital forensics disciplines developed – first was with the help of ad-hoc tools and techniques developed by practitioners who took it as a hobby, while the second being developed by scientific community. In 1992, the term “Computer Forensics”was used in academic literature.
After the development of digital forensics to a certain level, there was a need of making some specific standards that can be followed while performing investigations. Accordingly, various scientific agencies and bodies have published guidelines for digital forensics. In 2002, Scientific Working Group on Digital Evidence (SWGDE) published a paper named “Best practices for Computer Forensics”. Another feather in the cap was a European led international treaty namely “The Convention on Cybercrime” was signed by 43 nations and ratified by 16 nations. Even after such standards, still there is a need to resolve some issues which has been identified by researchers.
Since first ever computer crime in 1978, there is a huge increment in digital criminal activities. Due to this increment, there is a need for structured manner to deal with them. In 1984, a formalized process has been introduced and after that a great number of new and improved computer forensics investigation processes have been developed.
A computer forensics investigation process involves three major phases as explained below −
The first phase of digital forensics involves saving the state of the digital system so that it can be analyzed later. It is very much similar to taking photographs, blood samples etc. from a crime scene. For example, it involves capturing an image of allocated and unallocated areas of a hard disk or RAM.
The input of this phase is the data acquired in the acquisition phase. Here, this data was examined to identify evidences. This phase gives three kinds of evidences as follows −
Inculpatory evidences − These evidences support a given history.
Exculpatory evidences − These evidences contradict a given history.
Evidence of tampering − These evidences show that the system was tempered to avoid identification. It includes examining the files and directory content for recovering the deleted files.
As the name suggests, this phase presents the conclusion and corresponding evidences from the investigation.
Digital forensics deals with gathering, analyzing and preserving the evidences that are contained in any digital device. The use of digital forensics depends on the application. As mentioned earlier, it is used mainly in the following two applications −
In criminal law, the evidence is collected to support or oppose a hypothesis in the court. Forensics procedures are very much similar to those used in criminal investigations but with different legal requirements and limitations.
Mainly corporate world uses digital forensics for private investigation. It is used when companies are suspicious that employees may be performing an illegal activity on their computers that is against company policy. Digital forensics provides one of the best routes for company or person to take when investigating someone for digital misconduct.
The digital crime is not restricted to computers alone, however hackers and criminals are using small digital devices such as tablets, smart-phones etc. at a very large scale too. Some of the devices have volatile memory, while others have non-volatile memory. Hence depending upon type of devices, digital forensics has the following branches −
This branch of digital forensics deals with computers, embedded systems and static memories such as USB drives. Wide range of information from logs to actual files on drive can be investigated in computer forensics.
This deals with investigation of data from mobile devices. This branch is different from computer forensics in the sense that mobile devices have an inbuilt communication system which is useful for providing useful information related to location.
This deals with the monitoring and analysis of computer network traffic, both local and WAN(wide area network) for the purposes of information gathering, evidence collection, or intrusion detection.
This branch of digital forensics deals with forensics study of databases and their metadata.
Digital forensics examiners help to track hackers, recover stolen data, follow computer attacks back to their source, and aid in other types of investigations involving computers. Some of the key skills required to become digital forensics examiner as discussed below −
A digital forensics investigator must be an outstanding thinker and should be capable of applying different tools and methodologies on a particular assignment for obtaining the output. He/she must be able to find different patterns and make correlations among them.
A digital forensics examiner must have good technological skills because this field requires the knowledge of network, how digital system interacts.
Because the field of digital forensics is all about solving cyber-crimes and this is a tedious task, it needs lot of passion for someone to become an ace digital forensic investigator.
Good communication skills are a must to coordinate with various teams and to extract any missing data or information.
After successful implementation of acquisition and analysis, a digital forensic examiner must mention all the findings the final report and presentation. Hence he/she must have good skills of report making and an attention to detail.
Digital forensic investigation offers certain limitations as discussed here −
One of the major setbacks of digital forensics investigation is that the examiner must have to comply with standards that are required for the evidence in the court of law, as the data can be easily tampered. On the other hand, computer forensic investigator must have complete knowledge of legal requirements, evidence handling and documentation procedures to present convincing evidences in the court of law.
The effectiveness of digital investigation entirely lies on the expertise of digital forensics examiner and the selection of proper investigation tool. If the tool used is not according to specified standards then in the court of law, the evidences can be denied by the judge.
Another limitation is that some individuals are not completely familiar with computer forensics; therefore, many people do not understand this field. Investigators have to be sure to communicate their findings with the courts in such a way to help everyone understand the results.
Producing digital evidences and preserving them is very costly. Hence this process may not be chosen by many people who cannot afford the cost.