CHFI Data Acquisition and Duplication 4 — Questions and Answers
Question 1: What is the Device Configuration Overlay (DCO) and how does it differ from the HPA?
- DCO is set by the user; HPA is set by the manufacturer at the factory
- DCO is configured by the manufacturer or OEM to limit drive capacity; HPA is user-configurable (Correct answer)
- DCO stores partition tables; HPA stores firmware
- DCO and HPA are different names for the same feature
Correct answer: DCO is configured by the manufacturer or OEM to limit drive capacity; HPA is user-configurable
The DCO is typically set by manufacturers to standardize drive capacity across product lines, while the HPA can be set by the user or OS to hide data; both are invisible to the OS.
Question 2: A forensic examiner is acquiring a drive from a Mac with Apple Silicon (M1/M2). What is a key challenge compared to Intel-based Macs?
- M1/M2 Macs use a different file system (APFS) that no tools support
- Target Disk Mode is not available; acquisition requires OS-level tools or JTAG methods (Correct answer)
- M1/M2 drives use SCSI, which is incompatible with standard write blockers
- Apple Silicon encrypts RAM, preventing all live acquisition
Correct answer: Target Disk Mode is not available; acquisition requires OS-level tools or JTAG methods
Apple Silicon Macs removed Target Disk Mode, making traditional hardware-based acquisition impossible and requiring alternative methods like using Apple Configurator or specialized JTAG hardware.
Question 3: Which dcfldd command option generates a hash of the acquired image simultaneously during the imaging process?
- --verify
- hashlog= (Correct answer)
- conv=hash
- bs=hashmode
Correct answer: hashlog=
dcfldd's 'hashlog=' option writes a running hash (MD5 or SHA-1) to a specified log file as the image is being created, enabling simultaneous acquisition and verification.
Question 4: What is 'forensic soundness' in the context of data acquisition?
- The absence of audio data from the acquired image
- Ensuring the acquisition process does not alter original evidence and can be independently verified (Correct answer)
- Using only government-approved forensic software
- Completing acquisition within a legally required time window
Correct answer: Ensuring the acquisition process does not alter original evidence and can be independently verified
Forensic soundness means the acquisition method preserves original evidence without modification and produces results that can be independently repeated and verified.
Question 5: When creating a forensic image of a RAID array, what is the RECOMMENDED approach?
- Image each individual disk separately, then reassemble the RAID virtually in analysis software (Correct answer)
- Power off the RAID controller before imaging to prevent parity updates
- Use the RAID controller's native export function for best results
- Image only the parity disk since it contains all data
Correct answer: Image each individual disk separately, then reassemble the RAID virtually in analysis software
Imaging each disk individually and then using forensic software to virtually reconstruct the RAID ensures the original disks are not modified and allows flexible analysis.
Question 6: What is the significance of 'slack space' in forensic data acquisition?
- Slack space is only present on FAT file systems and contains no useful data
- Slack space between the end of a file and the end of its last cluster may contain remnants of previously deleted data (Correct answer)
- Slack space is the unused area in a drive's HPA
- Slack space refers to unused RAM during acquisition that slows the process
Correct answer: Slack space between the end of a file and the end of its last cluster may contain remnants of previously deleted data
File system slack (RAM slack + drive slack) occupies the space between a file's logical end and its allocated cluster boundary, which may contain overwritten fragments of old data.
Question 7: A hardware write blocker fails to initialize with a specific NVMe SSD. What is the BEST alternative to preserve evidence integrity?
- Proceed without a write blocker and document the decision
- Boot the suspect machine from a trusted forensic Linux live CD with software write blocking enabled (Correct answer)
- Image the drive without any write protection to save time
- Remove the NVMe drive and attach it via a standard SATA adapter
Correct answer: Boot the suspect machine from a trusted forensic Linux live CD with software write blocking enabled
Booting from a trusted forensic live environment (e.g., CAINE or Tails with forensic mode) enables software write blocking for interfaces where hardware write blockers are not yet available.
CHFI Data Acquisition and Duplication 4
What is the Device Configuration Overlay (DCO) and how does it differ from the HPA?