Forensics 2
Objectives and Framework of the Digital Forensics Laboratory
The fundamental goal of a forensic investigation is the rigorous application of the six established forensic steps. This lecture serves as a guide for investigators to understand how to operate within a laboratory environment, ensuring that every action is optimized for the integrity of evidence and the ultimate success of the case. The instruction covers specific organizational roles, essential gear, laboratory setup, and industry best practices. It is important to note that these guidelines are not necessarily a universal industry-wide agreement, nor do they strictly reflect the organizational structures of every specific employer. Furthermore, any mention of vendors or products within this context does not constitute a formal endorsement, but rather serves as an illustration of practical tools used in the field.
Organizational Roles and Responsibilities
A professional forensic laboratory is structured around six key roles that maintain the chain of custody and ensure expert handling of evidence. The Manager holds the highest authority, overseeing case creation and personnel assignment. The Laboratory Technician focuses on the physical state of the hardware, including repairs and preparation of internal components. The Acquirer is specialized in extracting data while maintaining total integrity. The Forensic Analyst (or Examiner) performs the deep-dive investigation to answer specific intelligence requirements. The Cyber Threat Intelligence (CTI) Analyst distills findings into broader strategic intelligence for the security community. Finally, the Researcher or Method Developer creates new techniques for acquisition and analysis to keep pace with evolving technology.
Administrative Management and Case Coordination
The Manager is responsible for the administrative lifecycle of a forensic case. Cases must be assigned unique, ordered identification numbers, often utilizing standards such as UUID version 7 (e.g., ) to ensure they are time-ordered and distinguishable. Because complex UUIDs are difficult to communicate, the manager also assigns an easily remembered code name, such as "OP CYBER". Beyond identification, the manager prioritizes cases based on urgency and allocates personnel to specific phases of the operation. For example, in a high-priority case, the manager might assign Alice to physical preparation, Bob and Carol to write-only acquisition, Carol and others to read-only analysis, and Dave to CTI and reporting.
Evidence tracking is further detailed through a standardized identification system for individual items. Each item is assigned a letter corresponding to the location of seizure and a number indicating the device count at that location. For instance, in "OP CYBER", evidence from Data Center Oslo (Location A) would be labeled A-1 for the server and A-2 for the NAS, while a laptop from a workplace (Location B) would be B-1. These IDs are used to reference evidence throughout the forensic process and dictate where items are stored in dedicated facilities, such as SYSBEL fire-resistant cabinets.
Case management software is used to maintain the chain of custody and facilitate collaboration. Examples of such platforms include Gogs.io, GitLab, Trello, Jira, and Basecamp. These tools manage authentication, authorization, and information dissemination. Using signed commits allows the lab to track exactly who was responsible for what action, while Continuous Delivery (CD) pipelines can be utilized to automate the generation of forensic reports.
Laboratory Technician Operations and Hardware Preparation
The Laboratory Technician is tasked with the physical handling and preservation of evidence. This involves repairing broken parts and cleaning devices that may have been exposed to external elements or moisture. A critical part of the role is preparing devices for data extraction, which may require removing storage units like HDDs or Flash memory, or exposing internal buses such as JTAG, UART, SPI, and I2C.
Technicians must adhere to strict Electrostatic Discharge (ESD) safety protocols to prevent damage to sensitive electronics. This includes utilizing equipment like the Combo Tester X3 to verify the status of footwear and wrist straps. Specialized tools are required for modern hardware, such as IFIXIT teardown kits and ESD-safe workspaces. For mobile devices or tablets, technicians often use heating pads, such as the CPB heating pad (Model 2023.03), to facilitate the replacement of screens and batteries. Other essential laboratory equipment includes soldering irons, logic analyzers, microscopes, voltmeters, external power supplies, and oscilloscopes.
Data Acquisition and Preservation Strategies
The Acquirer is responsible for extracting data in a manner that preserves its absolute integrity, typically through physical acquisition and digital fingerprinting. A cornerstone of this process is the 3-2-1 strategy: maintaining total copies of the data, using different media types (such as an SSD and Tape), and keeping copy off-site in an encrypted, self-hosted environment. The preservation process often involves command-line tools like . For instance, an acquirer might execute followed by generating a hash with to create a digital fingerprint. This hash is then verified using to ensure the raw image matches the original source.
Acquisition can range from straightforward bit-for-bit (physical) copies to complex logical copies where only specific files are extracted. In difficult cases, the acquirer may need to develop exploit chains or deal with proprietary black-box software and hardware combinations. To prevent human error and adhere to Locard's Exchange Principle—which suggests that every contact leaves a trace—investigators must use multi-purpose hardware write blockers. These devices ensure that data flows only from the evidence to the forensic machine, preventing accidental writes that would contaminate the evidence.
Forensic Analysis and Intelligence Requirements
The Forensic Examiner conducts the investigation by applying the 5W1H framework: What, Who, Where, When, Why, and How. The primary goal is to answer Intelligence Requirements (IR) set by managers, colleagues, legal prosecution, or CTI analysts. This phase is highly complex and spans various domains, including Windows, POSIX systems, mobile phones, and memory forensics.
Practical application of analysis includes determining which specific machines or networks were involved and reconstructing user timelines (logins, file access, emails) to show the sequence of events. Analysts rebuild attack methodologies, identifying exploited vulnerabilities and malware. They investigate data breaches to find exactly what data was exfiltrated and map communication patterns across email and chat apps to reveal participants. By tracing IP addresses, geolocation artifacts, and network logs, they identify the attacker's origin and establish the duration of the compromise. In fraud cases, they analyze the content and coordination of communications, including the use of encryption or code words. They also reconstruct specific user activities on workstations leading up to critical events, detailing the exact commands issued and configuration changes made.
Cyber Threat Intelligence and Research Development
The CTI Analyst extracts distilled intelligence from multiple cases to provide decision support for management. They share Tactics, Techniques, and Procedures (TTPs) and Indicators of Compromise (IOCs)—such as IP addresses, domains, and file hashes—with the broader information security community. This work supports Security Operations Centers (SOC) by informing SIEM rules, EDR policies, and IDS signatures. Simultaneously, Researchers and Method Developers work to advance the lab's capabilities by creating new techniques for acquisition and analysis. Their work covers applications, operating systems, file systems, network protocols, and hardware, as well as utilizing Open Source Intelligence (OSINT) to stay ahead of technical challenges.
Live Forensics Procedures
Live forensics refers to on-site investigations of running information systems, contrasting with traditional lab-based digital forensics. The objective is to capture volatile data that would be lost if the system were powered down, such as RAM, active network connections, and running processes. Because of the delicate nature of live systems, data must be acquired in the Order of Volatility. Investigators must minimize changes to the system, document every action meticulously, and typically operate in three-person teams consisting of one Manager and two Technicians.
Preparation for live forensics involves specialized gear, such as a cheat sheet of relevant devices, USB flash drives pre-loaded with bootable operating systems (like Tails, Kali, or Windows PE), and forensic tools for different OS environments. A robust Network Attached Storage (NAS) unit is often used for acquisition, requiring features like NVME/PCIe 4.0 support, USB 4.0, and Dual 10-Gigabit Ethernet to ensure high-speed data transfer. The NAS must have at least dual-disk redundancy for preservation and significant storage capacity. Additional field gear includes cameras for documenting the scene and power banks to maintain system uptime.
Network Segmentation and Lab Architecture
A forensic lab's network architecture is segmented to maintain security and integrity. Physical handling and seizure occur at the entry point, leading to a Write-Only environment for acquisition. Data then moves to a Read-Only environment where Analysts perform their work. The Research and Method Development zone is separate, often requiring access to the internet for OSINT and software needs. To maintain the isolation of the internal forensic zones from the public internet, a "Sneakernet" approach is often used, where tools and digital acquisitions are moved between segments using physical media rather than network connections. In this architecture, solid lines indicate network connectivity while dashed lines represent air-gapped or non-connected segments.
Digital Forensics Tool Starter Pack
For the initial implementation of forensic tasks, several open-source and standard tools are recommended. These should be run within a Virtual Machine (VM) for safety and organization. The starter pack includes:
: For data acquisition.: A comprehensive large toolkit for file system analysis.and: Specifically for Windows forensics.: For extracting image metadata.: For database analysis.: For working with proprietary Expert Witness Format (EWF) files.: For network forensics and packet analysis.: For password cracking and recovery.: For secure Open Source Intelligence gathering.
These tools form the baseline for practical workshops and day-to-day forensic operations, allowing investigators to move from installation to active evidence analysis.