Digital Evidence Collection and Preservation in Computer Network Forensics

Introduction

In an era where the digital domain permeates every aspect of our lives, the vast networks interconnecting devices serve as both a blessing and a curse. While they introduce conveniences, unparalleled speed, and a globalized lifestyle, they also bring inherent vulnerabilities. Malicious activities, from data breaches to cyber espionage, highlight the pressing need for vigilance and scrutiny within these networks. This is where computer network forensics steps in.

Computer network forensics, often referred to as 'digital forensics' in a wider context, is the meticulous process of capturing, analyzing, and interpreting the digital evidence left on computer networks. Much like a detective pieces together clues from a crime scene, digital forensic experts decode these digital trails, seeking answers to questions like “Who did this?”, “How?”, and “Why?”.

As the scale and sophistication of cyber-attacks grow, the significance of computer network forensics rises in tandem. It not only aids in identifying and prosecuting cybercriminals but also provides organizations with insights to strengthen their security by learning from past vulnerabilities. Amidst the rapid pace of digital transformations, investing in network forensics today can prevent expensive repercussions in the future.

When addressing computer-related crimes, digital evidence is the linchpin of any investigation. These consist of bytes and bits, logs and packets, all acting as testimonies to a cyber event. Whether it's a timestamp in a log file indicating unauthorized access or a sequence of packets documenting data exfiltration, digital evidence is instrumental in piecing together the story behind the crime.

Figure 1.

Transformation of confiscated material into evidence

Cyber forensics is a rigorous investigative approach that produces evidence robust enough for legal proceedings. This methodical process involves the collection, processing, interpretation, and presentation of undeniable digital facts pertaining to online crimes in legal contexts. In the current age of ubiquitous computing, forensic methodologies have attracted attention from both researchers and professionals. Their evolving scope and consistent relevance over time is evident, as noted by S. Vinjosh Reddy, K. Sai Ramani, K. Rijutha, S. Mohammad Ali, and C. H. Pradeep Reddy in 2010. As the discipline expands, so too do the definitions and requirements for supportive tools and techniques. Approximately every few years, the procedural phases of network forensics experience revisions and updates.

Data undergoes significant transformation as it progresses through various stages: starting from raw data, evolving into processed information, then solidifying into concrete evidence, and ultimately reaching a form that's admissible in court, as depicted in Figure 1. Depending on the particular medium involved in cybercrime, cyber forensic terms can be categorized, as illustrated in Figure 2:

Network Forensics: The method entails systematically observing and analyzing network traffic to gather information, secure legal evidence, or detect intrusions. This perspective is supported by the findings of S. Almulla, Y. Iraqi, and A. Jones in 2013. Essentially, the process revolves around collecting and evaluating network-related data to identify security breaches.

Web Forensics: A variety of tools and technologies have been explored to facilitate effective responses based on evidence collection. The primary goal is to unearth digital evidence across the internet. When applied in an online context, this discipline is commonly termed Network Forensics.

E-mail Forensics: Examining electronic emails using a range of tools and methodologies reveals details and data associated with cybercrimes. The evidence obtained from this investigation is subsequently presented in court.

Enterprise Forensics: This category aims to protect the consistency and real-time integrity of information within an organization while preventing security breaches. It predominantly focuses on a proactive approach, with lesser emphasis on evidence collection. In contrast, System Forensics is used to gather and compile evidence from computing devices. Setting it apart from other forensic techniques, this method is invoked when an offense involves standalone devices.

Figure 2.

Cyber forensics terminologies