Digital Forensics
Understanding Digital Forensics
Digital forensics identifies, preserves, analyzes, and presents digital evidence. It encompasses various techniques and tools for investigating and recovering data from digital devices such as computers, mobile phones, storage media, and network systems. The primary goal is to uncover and interpret evidence that can be used in legal proceedings or to answer specific investigative questions. This process involves a systematic approach to gathering and analyzing digital information while maintaining the integrity of the evidence to ensure its admissibility in court.
The digital forensics workflow typically begins with acquiring digital evidence, where forensic experts create a forensic image or make a bit-by-bit copy of the original drive or device. This step is crucial to preserving the original data and metadata without altering the contents. Subsequently, the acquired data undergoes a thorough analysis, which may involve keyword searches, file carving, metadata examination, and other methods to recover relevant information.
It entails interpreting and documenting findings, often in the form of detailed reports or presentations that outline the discovered evidence and the methods used to obtain it. Forensic investigators adhere to strict protocols and standards to ensure the accuracy, completeness, and validity of their findings.
Understanding the Chain of Custody
Chain of Custody is a crucial component of digital forensics, providing a documented record of the handling and storage of digital evidence. This process ensures the integrity of the evidence by meticulously tracking its movement from the time it is collected until its presentation in a legal setting. By maintaining a secure and transparent Chain of Custody, digital forensic experts can demonstrate that the evidence has not been tampered with, preserving its admissibility and credibility in court. This tracking is essential in establishing the authenticity and reliability of digital evidence, playing a fundamental role in investigations and legal proceedings.
Understanding Data Acquisition and Methods of Acquisition
Data acquisition is a critical first step in conducting digital forensics. It involves carefully collecting and preserving electronic evidence from various digital devices.
To ensure the integrity and admissibility of the evidence, it is imperative to follow a systematic approach to data acquisition. This includes identifying the relevant devices, utilizing proper tools and techniques for extraction, and maintaining a detailed chain of custody. It is crucial to document the acquisition process thoroughly, including the date, time, and individuals involved, to establish a clear audit trail for the evidence.
Forensic data acquired is stored in 3 different formats:
Raw - makes it possible to write bit-stream data to files.
Proprietary - Offers options to compress or not to compress image files.
AFF (Advanced forensics formats) - provides compressed or uncompressed image files. It provides space in the image files for metadata—a simple design with extensibility.
Data Acquisition Methods:
Disk to Image file - You can make more than one copy. Copies are bit-to-bit replications of the original drive. They are compatible with different tools.
Disk-to-disk copy - Used when disk-to-image copy is not possible. It can adjust to the disk’s geometric configuration.
Logical disk-to-disk or disk-to-data file - Capture only specific files of interest to the case.
Sparse data copy - collects fragments of unallocated data.
Several tools are available, and lossless compression is acceptable. However, planning your digital evidence contingencies is essential, such as making a copy of each acquisition.
dd: A Unix/Linux/macOS command that can perform disk image acquisition dd if=/dev/sda of=/mnt/usbdrive/evidence.dd