Use of Write-Blockers in Evidence Collection

How Write-Blockers Protect Digital Evidence During Collection

The use of write-blockers in evidence collection is a critical step in computer forensics. Write-blockers are tools that prevent any data from being changed or written back to a digital device like a hard drive or USB stick while investigators make a copy of its contents.

When collecting digital evidence, maintaining the original data’s integrity is very important. If even a small change happens accidentally, the evidence may become unusable in court. Write-blockers ensure the original device stays exactly the same by blocking any write commands from the forensic computer or software while the evidence is being copied.

There are two main types of write-blockers:

• Hardware write-blockers: These devices connect between the forensic workstation and the evidence drive. They physically stop all write signals from reaching the drive.
• Software write-blockers: These are applications that control the operating system to prevent writing to the evidence drive during imaging or analysis.

Hardware write-blockers are preferred because they provide a higher level of assurance that no writes occur, as they work independently of the computer’s operating system.

Steps for Using a Write-Blocker in Evidence Collection

1. Connect the write-blocker to the forensic workstation.
2. Attach the suspect device (hard drive, USB) to the write-blocker.
3. Verify that the write-blocker is working, usually by checking indicator lights or using a test function.
4. Create a forensic image (copy) of the device using imaging software.
5. Confirm the image’s integrity by comparing hash values of the original device and the copy.

Using a write-blocker ensures the evidence is not altered during this process, which protects its reliability for investigators, lawyers, and the court.

Without write-blockers, accidental writes could happen during the copying process, such as updating timestamps or system files. This risks damaging the evidence’s integrity, leading to challenges in its admission during legal proceedings.

In summary, the use of write-blockers in evidence collection is a best practice that safeguards digital evidence. It helps maintain the original state of devices so the data can be trusted for forensic analysis and legal use.