[Common Sec] Digital Forensics: A Systematic Approach to Cyber Incident Response

Purpose and Definition of Forensics

In today’s digital environment, cyber incidents are becoming increasingly frequent and complex. These incidents can have severe impacts on business continuity, data security, and legal accountability for organizations. Understanding the purpose and definition of forensics is critical to accurately determining the cause of cyber incidents, preventing recurrence, and clarifying accountability. Forensics goes beyond mere technical investigation; it encompasses comprehensive activities such as collecting legally admissible evidence, identifying root causes, and enhancing organizational security. This article explores the purpose and definition of forensics, detailing the four key procedures: collection, examination, analysis, and reporting.

1. Collection

1) Definition

The collection phase involves swiftly securing and preserving incident-related data without damage or alteration, making it ready for further investigation and analysis. Maintaining data integrity is essential in this step.

2) Importance of Collection

Timely data collection is crucial to avoid the risk of evidence loss or tampering. Digital data, in particular, is at risk of being overwritten due to limited storage space, making immediate collection after an incident essential.

3) Key Activities

• Identifying and Acquiring Data:
  • Identify and secure relevant data, such as logs, network traffic, and system state information.
  • Prioritize critical data based on the scope of the incident.
• Maintaining Data Integrity:
  • Generate and store hash values to prevent data tampering.
  • Preserve original data while using duplicates for analysis.
• Evidence Storage and Management:
  • Store data on separate devices like external drives for secure protection.
  • Create multiple backup copies to reduce the risk of data loss.

4) Significance

The thoroughness of the collection phase determines the reliability of the entire forensic process. Inadequate data collection can lead to skewed results in subsequent investigations and analyses.

2. Examination

1) Definition

The examination phase involves systematically reviewing collected data to identify critical information related to the incident, laying the groundwork for further analysis.

2) Importance of Examination

Forensic examination goes beyond simple data review; it identifies relevant information while excluding unnecessary data, clarifying the core causes of the incident. This process sets the direction for the analysis phase.

3) Key Activities

• Log and Event Data Analysis:
  • Review logs such as Windows Event Logs and firewall logs to detect abnormal activities.
  • Arrange log data chronologically to pinpoint the incident timeline.
• Recovering Deleted Data:
  • Restore corrupted or deleted files to collect all incident-related data.
  • Analyze metadata in file systems to trace file modification history.
• Creating a Timeline:
  • Organize collected data in chronological order to visualize the sequence of events.
  • Combine network traffic and user activities for a comprehensive view.
• Detecting Anomalies:
  • Compare data with normal baselines to identify unusual activities, configuration changes, or data losses.

4) Significance

The examination phase is critical for comprehensively understanding all incident-related data and establishing a solid foundation for efficient analysis.

3. Analysis

1) Definition

The analysis phase involves in-depth interpretation of the examined data to determine the cause and progression of the incident, providing actionable insights to prevent future occurrences.

2) Importance of Analysis

Forensic analysis facilitates a holistic understanding of the incident, uncovers the attacker’s methods and entry points, and provides essential information for improving organizational security.

3) Key Activities

• Network Traffic Analysis:
  • Use tools like Wireshark and TCPDump to analyze captured network data.
  • Identify malicious codes or abnormal traffic patterns.
• Identifying Attack Paths and Actors:
  • Determine the tactics, techniques, and procedures (TTPs) used by the attacker.
  • Investigate actions of internal or external actors to clarify accountability.
• Vulnerability Analysis:
  • Identify weaknesses in systems and networks, proposing mitigation strategies.
  • Compare with pre-incident baselines to analyze changes.
• Reconstructing Incident Progression:
  • Recreate the sequence of events to understand the overall impact and course of the incident.

4) Significance

The analysis phase is essential for strengthening security frameworks and designing actionable measures to prevent incident recurrence.

4. Reporting

1) Definition

The reporting phase involves systematically organizing analysis results into a document for organizational decision-makers and legal entities.

2) Purpose of Reporting

Forensic reports do more than explain incidents; they clearly identify root causes, propose response measures, and ensure compliance with legal and regulatory requirements.

3) Key Activities

• Summarizing Results:
  • Clearly outline the cause, progression, and outcomes of the incident in the report.
  • Use visual aids to ensure clarity for stakeholders.
• Documenting Evidence:
  • Detail the collected evidence and analysis procedures to ensure legal validity.
  • Present data in a format that guarantees integrity and reproducibility.
• Proposing Recommendations:
  • Suggest security improvements and response strategies to prevent recurrence.
  • Include the need for procedural improvements and additional training.
• Meeting Legal Requirements:
  • Prepare the report in compliance with legal standards, ensuring it can be submitted to regulatory authorities if needed.

4) Significance

The reporting phase produces the final deliverable of forensics, providing the foundation for organizational decision-making, legal responses, and security policy enhancements.

Conclusion

Forensics is more than just data analysis; it is a crucial tool for strengthening an organization’s security posture in all aspects of incident response. Through the four procedures of collection, examination, analysis, and reporting, forensics identifies the causes of incidents, enhances organizational security, and provides concrete strategies to prevent recurrence. Understanding the purpose and definition of forensics is the first step in effectively safeguarding digital assets and legal responsibilities.