CHFI (312-49) Digital Forensics Simulation

Welcome to this digital forensics scenario. You will analyze evidence handling procedures and apply proper Chain of Custody concepts to ensure evidence admissibility in a court of law.

Investigation Scenario

An embezzlement investigation at a high-profile investment bank in Charlotte, North Carolina has been ongoing for six months. Digital forensics investigators executed a search warrant and seized multiple storage devices, including a RAID array and several encrypted USB flash drives believed to contain the hidden financial ledgers.

Because of the prolonged nature of the investigation and the volume of data, the evidence has moved from the incident scene to the intake department, then to a secure evidence vault, checked out by forensic examiners for imaging, and later audited by financial experts. The defense attorney has filed a motion to suppress the digital evidence, claiming it was subjected to tampering during these multiple transfers.

Evidence Collected

> CASE ID: INV-2025-094-CLT
> EVIDENCE ITEM: EVD-001 (Seagate 2TB HDD, SN: Z9B8X7V6)
> MD5 ACQUISITION HASH: 7d9f8a8b1c4e9d2f6a7b3c4d5e6f7a8b

--- TRANSFER LOG EXCERPT ---
10-01-2025 09:14 | Seized at Scene | By: Inv. R. Smith (Badge #884)
10-01-2025 14:30 | Transferred | From: Inv. R. Smith | To: Intake Vault (C. Davis)
10-03-2025 08:00 | Checked Out | From: Intake Vault | To: Examiner T. Jones
10-03-2025 18:45 | Returned | From: Examiner T. Jones | To: Intake Vault

STATUS: HASH VERIFIED PRE- AND POST-EXAMINATION. NO DISCREPANCIES.

Question

In a prolonged embezzlement investigation at an investment bank in Charlotte, North Carolina, seized ledgers and storage devices move through multiple custodians, including intake personnel, forensic examiners, and auditors. Each transfer must be documented to address potential claims of evidence tampering during testimony. Which documentation element establishes this continuous record of handling and transfer?

Forensic Hint: We are looking for the definition of the document that tracks the chronological history and geographic movement of the artifact, tracking exactly who had it, when they had it, and where it went.

Expert Analysis

1. What the Evidence Shows

The provided transfer log excerpt demonstrates chronological tracking of the Seagate HDD (EVD-001). It notes the date, time, originating custodian, and receiving custodian for every physical movement of the device. The hash verification confirms logical integrity, but the physical log confirms handling integrity.

2. Forensic Stage

This falls under the Preservation / Chain of Custody phase. Proper preservation requires not just preventing data alteration (via write-blockers and hashing), but maintaining a continuous legal record of possession.

3. Why the Correct Answer is Correct

Option B is correct. The Chain of Custody (CoC) is a legal document that provides a chronological, continuous record of the seizure, custody, control, transfer, analysis, and disposition of physical or electronic evidence. Documenting the movement of evidence from its origin through examination is the exact purpose of the CoC to refute tampering claims.

4. Why Others are Wrong

A is incorrect: While a CoC includes individuals, merely listing individuals and actions describes an activity log or access control list, not the continuous geographic and physical transfer record.

C is incorrect: Describing procedures for collecting and storing evidence refers to Standard Operating Procedures (SOPs) or forensic guidelines, not case-specific evidentiary tracking.

D is incorrect: Identifying the collector and basic descriptors refers to an evidence tag or evidence label, which is placed on the item but does not track its ongoing movement over time.

5. Real-World Forensic Action

When presenting evidence in court, the forensic examiner must produce the CoC form alongside the final report. If there is a "break" in the chain (e.g., the log doesn't show how the evidence got from the vault to the auditor), the defense will file a motion to suppress, arguing the evidence could have been altered during the undocumented period.

MINI LESSON: Chain of Custody (CoC) Principles

  • Continuous Record: The CoC must account for 100% of the timeline. There can be no chronological gaps.
  • Signatures: Both the person relinquishing and the person receiving the evidence must sign/timestamp the transfer.
  • Hash Binding: In digital forensics, physical CoC is usually paired with logical hashing. The MD5/SHA value acquired at intake must match the value calculated prior to any subsequent examination.
  • Secure Storage: Between transfers, evidence must reside in a secure, access-controlled environment (e.g., an evidence locker or vault).

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