CHFI Computer Forensics Fundamentals and Process Practice Question
A forensic examiner uses a hardware write blocker when imaging a suspect's hard drive. What is the primary function of a hardware write blocker?
⚠ Common exam trap
EC-Council often tests the distinction between the function of a write blocker (preventing writes) and its physical interface (e.g., USB), leading candidates to mistakenly choose the interface option as the primary function.
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
✓
To prevent any data from being written to the suspect drive
A hardware write blocker is a device placed between the suspect drive and the forensic workstation that intercepts and blocks any write commands from the host system. Its primary function is to ensure that no data—such as file system metadata, temporary files, or operating system writes—can be written to the suspect drive, thereby preserving the original evidence in a forensically sound manner. This is critical for maintaining the integrity of the evidence and ensuring it is admissible in court.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
To encrypt the data on the suspect drive
Why it's wrong here
Hardware write blockers operate at the ATA/SCSI command level, permitting only read commands and discarding write commands; they never transform the data. Encryption would alter the suspect drive's contents or produce an encrypted image, which would compromise the integrity of the original evidence and violate forensic best practices. Thus, write blockers are not encryption tools; they are preservation instruments.
- ✓
To prevent any data from being written to the suspect drive
Why this is correct
A hardware write blocker is designed to guarantee the integrity of digital evidence by intercepting write commands from the forensic host to the suspect drive. It allows read-only access at the physical interface, ensuring that no bytes are altered on the source media during acquisition or analysis. This preservation of the original evidence is essential for maintaining a chain of custody and for admissibility in court.
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To connect the suspect drive via USB
Why it's wrong here
Although many write blockers physically connect to a forensic workstation via USB or FireWire, that interface is just a convenience for the examiner. The core function is to enforce read-only access by controlling the bus protocol between the host and the suspect drive. Using a USB cable alone would allow the operating system to write metadata, timestamps, or file system changes to the drive, so a write blocker is not simply a connection tool.
- ✗
To increase the speed of data acquisition
Why it's wrong here
A hardware write blocker does not accelerate data acquisition; in fact, it may introduce slight latency as every command is inspected and filtered. Imaging speed depends on the interface and drive speed, not on the blocker, which is solely for ensuring that the source drive remains unchanged during forensic imaging. Any apparent speed gains would be coincidental and not the intended function.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CHFI practice question is part of Courseiva's free EC-Council certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CHFI exam.