In Depth

PC Disposal: Hard-Disk Risk

Are all those old hard drives you're getting rid of completely wiped clean of important company data? Don't be so sure.

By Simson Garfinkel

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In fact, there is no unclassified evidence that data on a modern hard drive can be recovered after it has been overwritten with just a single pass of random information. Some have made such claims, but no such recovery has ever been demonstrated in public. Today's hard drives are specifically designed not to work that way. When you save a new version of a Microsoft Word file on your hard drive, for instance, you want to get the new—not the old—version.

A growing number of businesses offer to properly sanitize, refurbish and reload your computers with "clean" software before the machines are repurposed within your organization or sold. Although outsourcing sounds attractive, I'm concerned that it is exceptionally difficult to audit those companies and make sure they are actually deleting your data.

In the end, preventive technology is a better solution to the sanitization problem. If you use an encrypted file system, you can sanitize a disk simply by erasing the key. I'd like to see that sort of technology built in to hard drives. Or better, perhaps someday soon, all disk drives will come with a self-destruct feature—just like Star Trek's Enterprise did!