4.8 Digital Forensics

Digital Forensics

Involves collecting and analyzing data after a security event to understand what happened, prevent future attacks, and support legal proceedings.

• Following best practices during data acquisition, analysis, and reporting is crucial since this evidence may be used years later in court.

• RFC 3227 outlines guidelines for proper evidence collection and archiving

Legal Hold

A formal request, often from a lawyer, to preserve specific data for legal reasons.

• This request is sent to a data custodian, who must locate and secure the electronically stored information (ESI) involved.

• The data is placed in a designated repository and must be preserved exactly as specified.

• May require extracting information from complex systems, such as converting email archives from proprietary formats to readable text.

Chain of Custody

Ensures digital evidence remains unchanged and traceable from the moment it’s collected.

• Like sealing physical evidence in a tamper-evident bag, digital evidence must be handled using secure processes—such as cryptographic hashes and digital signatures—to prove its integrity.

• Every time someone accesses the data, that action must be recorded.

• This documentation helps verify that the evidence viewed later is exactly what was originally collected.

Acquisition

The first step in digital forensics and involves collecting data from a variety of sources.

• Can include disk drives, system memory, firmware, virtual machines, or file systems.

• Data might come from multiple endpoints like servers, firewalls, or network devices.

• In virtual environments, a full VM snapshot can capture all relevant data.

• Important evidence may also be hidden in less obvious places—like log files, the recycle bin, browser bookmarks, saved credentials, or temporary folders.

Reporting

After acquiring data in a forensic investigation, it's crucial to thoroughly document how the data was collected and handled.

• Typically begin with a summary of the incident and the reasons for initiating data acquisition.

• Followed by a detailed, step-by-step account of the acquisition process, including all integrity checks and methods used to preserve the data's original state.

• Clear documentation allows third parties to verify that the evidence remains unchanged.

• In some cases, the report also includes a factual analysis of the data’s structure and relevance

• Conclusions about how the data relates to the security incident helps IT directly.

Preservation

Once data is acquired ensure it remains intact for potential legal proceedings, even years later.

• Copies should be made from the original source to prevent accidental modification during analysis (especially for volatile data like mobile devices, which could be remotely wiped).

• Preserving data while the system is live is often necessary, particularly on encrypted systems that lock when powered off.

• Ensures the data remains admissible in court, reinforcing that actions taken now can significantly impact future legal outcomes.

E-Discovery

Focuses solely on data acquisition—not analysis.

• Often supports legal or investigative efforts and works alongside broader forensic procedures.

• You might be asked to create a forensic image of a hard drive and provide it to a forensics team.

• Your role ends there; the team then examines the image for deleted files or relevant information.