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How to securely wipe hard drives

I often times get asked by friends and clients to refer them to a good tool for securely wiping their hard drives. If you’re decommissioning, selling, or returning a drive with sensitive or confidential data on it, you are right to take measures to wipe the drive.

Deleting files from a hard drive doesn’t actually delete them. Instead, it merely “marks” them as deleted, leaving the original data intact until the disk space is reused. It may be that even after that space is reused that partial remnants of the files still remain, and can be easily recovered. TechRepublic wrote up a good article backed by solid research that shows just how many drives contained easily-recoverable data. The results are unnerving, but they don’t have to be.

When wiping drives is a concern, you have two choices — completely wiping a drive that you’re no longer using — that is, if you’re going to part with it; or wiping only the “free space” of your computers hard drive that you’re still using, simply to make sure deleted files are actually gone and unrecoverable.

There are many good, free, easy-to-use utilities that do an excellent job of wiping your drives. Here’s are two that I’m most familiar with and can recommend:

Darik’s Boot and Nuke (DBAN) – (website) (download) – Wipes drives completely

Darik’s Boot and Nuke (“DBAN”) is a self-contained boot disk that securely wipes the hard disks of most computers. DBAN will automatically and completely delete the contents of any hard disk that it can detect, which makes it an appropriate utility for bulk or emergency data destruction.

Eraser – (website) (download) – Can do “free space”-only wiping

Eraser is an advanced security tool for Windows which allows you to completely remove sensitive data from your hard drive by overwriting it several times with carefully selected patterns. Eraser is currently supported under Windows XP (with Service Pack 3), Windows Server 2003 (with Service Pack 2), Windows Vista, Windows Server 2008, Windows 7 and Windows Server 2008 R2.

CCleaner – (website) – Free space and full drive wiping for Windows

Besides being an all-around great cleaner for the registry, CCleaner now includes the ability to wipe both full drives and free space only. A great utility for Windows users.

These are just two programs, and there are many more available.

If you’re a *nix user, Engadget points the way to the shred program. In a nutshell, the following command is what you’re looking for:

shred -vz -n 3 /dev/sda

This will write 3 passes of random data to /dev/sda (make sure that’s the right drive before you start!), followed by a 4th pass of zeros.  It takes some time, so if you don’t mind random (suspiciously random) data on the drive, you can skip the zeroing pass by omitting the z flag.

Do you have a suggestion for a utility that can securely wipe hard drive data? Do you have any questions or feedback on the above? Please voice your thoughts in the comments below! Thank you!

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