CHFI Computer Forensics Fundamentals and Process Practice Question

During a forensic investigation, the analyst needs to create a forensic image of a hard drive that also hashes the data during acquisition. Which command-line tool would be MOST appropriate for this task?

⚠ Common exam trap

The CHFI exam often tests the distinction between dd and dcfldd, trapping candidates who assume dd is sufficient because it can create a raw image, ignoring the explicit requirement for integrated hashing during acquisition.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

dcfldd

dcfldd is a modified version of dd that includes built-in hashing (e.g., MD5, SHA-1, SHA-256) during the imaging process, allowing the analyst to verify data integrity in real time without a separate hashing step. This makes it the most appropriate tool for creating a forensic image that also hashes the data during acquisition.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

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dd
Why it's wrong here
dd is a versatile Unix tool for raw bit-for-bit copying, but standard dd has no built-in hashing capability. An analyst using dd must run separate commands such as sha256sum or md5sum both before and after imaging to verify integrity, which adds time and risks a hash mismatch if the source changes during acquisition. Without an on-the-fly hash, every byte read is written but never independently verified during the copy, so dd alone fails the forensic requirement of contemporaneous integrity validation.
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fdisk
Why it's wrong here
fdisk is an interactive partitioning utility used to create, delete, and manage partition tables; it is not designed to read or write the entire block device as a raw image. Running fdisk does not produce a forensic image of the disk's contents, and any write operation with fdisk would alter disk metadata, potentially contaminating evidence. Therefore fdisk is categorically incompatible with forensic acquisition, which requires a bit-for-bit copy of the storage medium, not a partition layout operation.
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memdump
Why it's wrong here
memdump is a memory acquisition utility that reads physical memory, such as /dev/mem or /dev/kmem, to capture RAM contents including running processes, open sockets, and kernel structures. It is intended for volatile memory forensics, not for creating a bitstream copy of persistent storage, so it will not include file system metadata, deleted files, or unallocated disk space. Since the analyst needs a disk image, memdump targets the wrong evidence source and is unsuitable for this task.
✓
dcfldd
Why this is correct
dcfldd is an enhanced version of dd developed by the US DoD Computer Forensic Lab that embeds on-the-fly hashing using algorithms like md5, sha1, sha256, sha384, or sha512. It computes one or more hashes simultaneously while writing the image, and can also hash the input and output independently, providing immediate verification that the acquired image is identical to the source. With built-in hash logging, progress reporting, and the ability to write to multiple outputs, dcfldd is purpose-built for forensic imaging where integrity must be proven contemporaneously, making it the correct choice.

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CHFI Computer Forensics Fundamentals and Process Practice Question

Why each option matters

Option-by-option breakdown

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