During a forensic investigation, an analyst discovers that the suspect's hard drive was encrypted using BitLocker. The analyst has obtained the recovery key. Which of the following is the best next step to ensure data integrity?
Trap 1: Decrypt the drive using the recovery key and then create a forensic…
Applying the recovery key to decrypt the original drive in place is destructive from an evidentiary perspective: the controller performs writes that alter sector-level plaintext, encrypted metadata, filesystem journal, and access timestamps, contaminating the very evidence you must preserve. You also lose the pristine encrypted snapshot, which may be needed to prove how the encryption was configured, and any imaging afterward captures artifacts introduced by the decryption process. Always image the encrypted medium first and decrypt only a forensic clone.
Trap 2: Run a live analysis tool to extract encryption keys from memory.
Running a live tool to pull keys from memory can produce useful decryption credentials, but it does not produce a forensic image of the encrypted disk, and it involves executing code on the live system, changing memory state and potentially triggering anti-forensic or FDE lockdown routines. Even if key extraction succeeds, you still need a separate disk image to analyze user data; without an image, the keys are only a means to decrypt evidence you failed to collect. Volatile memory acquisition should be performed as a supplementary step — never as a substitute for imaging the disk.
Trap 3: Boot the suspect computer and copy files to an external drive.
Booting the suspect computer to copy files is a textbook contamination scenario: the boot process writes to the registry, prefetch, event logs, hibernation file, and filesystem metadata, and it can overwrite unallocated areas where deleted evidence resides. Manually copying selected files also snatches only active, visible data; you lose deleted files, slack space, and partition-level artifacts, creating an incomplete and legally indefensible evidentiary collection. The correct, non-invasive approach is to acquire a full disk image with the system powered off using a hardware write-blocker.
- A
Decrypt the drive using the recovery key and then create a forensic image.
Why wrong: Applying the recovery key to decrypt the original drive in place is destructive from an evidentiary perspective: the controller performs writes that alter sector-level plaintext, encrypted metadata, filesystem journal, and access timestamps, contaminating the very evidence you must preserve. You also lose the pristine encrypted snapshot, which may be needed to prove how the encryption was configured, and any imaging afterward captures artifacts introduced by the decryption process. Always image the encrypted medium first and decrypt only a forensic clone.
- B
Run a live analysis tool to extract encryption keys from memory.
Why wrong: Running a live tool to pull keys from memory can produce useful decryption credentials, but it does not produce a forensic image of the encrypted disk, and it involves executing code on the live system, changing memory state and potentially triggering anti-forensic or FDE lockdown routines. Even if key extraction succeeds, you still need a separate disk image to analyze user data; without an image, the keys are only a means to decrypt evidence you failed to collect. Volatile memory acquisition should be performed as a supplementary step — never as a substitute for imaging the disk.
- C
Create a forensic image of the encrypted drive, then decrypt the image.
Creating a bit-for-bit forensic image of the encrypted drive before any decryption preserves the original evidence in its native state, capturing the full encrypted volume, partition table, free space, and deleted data remnants. The analyst can then decrypt that image on a write-protected or isolated forensic workstation using the known recovery key or extracted keys, leaving the original exhibit untouched and maintaining chain of custody. This workflow is the accepted standard for full-disk-encrypted evidence because it separates acquisition from decryption and permits multiple independent analyses.
- D
Boot the suspect computer and copy files to an external drive.
Why wrong: Booting the suspect computer to copy files is a textbook contamination scenario: the boot process writes to the registry, prefetch, event logs, hibernation file, and filesystem metadata, and it can overwrite unallocated areas where deleted evidence resides. Manually copying selected files also snatches only active, visible data; you lose deleted files, slack space, and partition-level artifacts, creating an incomplete and legally indefensible evidentiary collection. The correct, non-invasive approach is to acquire a full disk image with the system powered off using a hardware write-blocker.