'Cleaned' hard drives reveal secrets

New Scientist ^ | 14:32 16 January 03 | Will Knight

[luckystarmom]

They do more than write all ones. Usually it is a pattern of 1's, then 0's, then 1's and 0's.

That was the first type of computer program I ever wrote for a defense company when I was just out of college.

It's very simple, but a disk won't be clean unless it is re-written.

[DensaMensa]

}If you have serious concerns with what data can be recovered from you hard drive, don't bother any approach that depends on the drive itself to overwrite the data.

Naw, I don't have any significant concerns beyond keeping email addresses away from collectors and sellers. But it sounds like anyone who does should schedule a carribean cruise and take a quiet walk around the rail in the middle of the night. [:/)

[general_re]

That is why the ONLY safe method (other than physical destruction) is multiple writes with different patterns. It seems that about 7 re-writes gets one pretty close to being unreadable.

Pretty close, but still not unreadable. I remember reading a paper from a fellow who was, using an electron microscope and some other exotic equipment, able to recover data that had been randomly overwritten as many as 30 times.

The equipment and techniques exist, AFAIK, to recover data regardless of the pattern or number of times it's overwritten. Obviously, though, very few people have information on their hard drives that make this sort of effort worthwhile, but the only way to really be sure is to physically destroy the drive and platters.

[Harley109]

I bought an IBM Aptiva from Goodwill and the "wiped," reformatted and clean rebooted hard drive told me way too much abut the former owner. This individual was a professional in his field, and I was just flat amazed of the value of what I learned and got from his old 'puter. I wish I could say ore about this, but that in and of itself would be unethical.

Fortunately for him I have scrupples and was just doing hands on learning on a mere 266 with an AMD K6 just to do just that, learn. I have had my ID stolen before, and I would never, never suffer anyone to ever go through that ordeal.

I keep ALL my hard drives now. When I resell any machine once used with personel data, it goes out with a new, or used by another person hard drive that has been formatted with a government wipe done to erase the old stuff as best as possible.

[Old Professer]

I remember Simson well from MIT in the early 80's.

From the article:

Simson Garfinkel and Abhi Shelat, graduate students at the Massachusetts Institute of Technology,

[VeritatisSplendor]

So he took a decade or so off and worked as a professional writer before going back to grad school -- what's the big deal?

[mlmr]

No big deal. Just an observation. My limited experience at MIT tells me that techie guys are usually young. He must be unusual.

[sd-joe]

"I don't believe this to be true."

It IS TRUE. AND you are correct in your logic also.

When a file is deleted, an index pointer to the file is removed, as it says, and thus the file is still there. However, the space the file is in, is now included in the AVAILABLE TO USE space on the disk. At some point, as new files are written, this space is written over as you suggest.

The point is, at any given time, recently deleted files are still there and available for recovery. Also, there is no insurance on WHEN the file will be overwritten. And worst, simply overwritting the file, one or several times, does not prevent it from being recovered by people with the right equipment.

[Old Professer]

Well, the time lapse piqued my curiosity, but yesterday I was too involved with the breaking weather here in Nashville to dig around for information on him. A quick Google reveals this bio (marked for publication) reveals:

Simson L. Garfinkel

Simson L. Garfinkel is a researcher in the field of computer security and commentator on information technology. As a researcher, Garfinkel is currently a graduate student at the Laboratory for Computer Science at the Massachusetts Institute of Technology, where he is working on his doctorate. Prior to joining LCS, Garfinkel founded Sandstorm Enterprises, a computer security firm that develops offensive information warfare tools used by businesses and governments to audit their systems. Prior to founding Sandstorm, Garfinkel founded Vineyard.NET, the Internet Service Provider (ISP) for Martha's Vineyard, in 1995. In 2000 he successfully negotiated the sale of Vineyard.NET to Broadband2Wireless (BB2W), a venture-funded broadband wireless ISP. When BB2W failed, Garfinkel negotiated the repurchase of Vineyard.NET from BB2W's bankruptcy court.

Besides his activities as a computer scientist and entrepreneur, Garfinkel has had an active career as popularizer of technology. After receiving his masters degree from Columbia University in 1988, Garfinkel spent 14 years writing for some of the nation's leading publications, including The Boston Globe, The San Jose Mercury News, The Christian Science Monitor, and Technology Review Magazine, in which he now publishes a regular column. He was one of the founding contributors of Wired Magazine, and still writes for Wired on an occasional basis. Garfinkel's popular articles have appeared in more than 50 publications including ComputerWorld, Forbes, The Nation, The New York Times, Omni and Discover.

Garfinkel is the author or co-author of twelve books on computing, published by O'Reilly and Associates, Springer-Verlag, and IDG Books. He is perhaps best known for his book Database Nation: The Death of Privacy in the 21st Century. Consumer advocate Ralph Nader called this book "A graphic and blistering indictment" of the techniques used by businesses to invade our privacy and our lives. Garfinkel's most successful book, Practical UNIX and Internet Security, has sold more than 125,000 copies since the first edition was published in 1991.

Garfinkel holds three degrees from the Massachusetts Institute of Technology and a masters of science degree from Columbia University. He is a member of the Association for Computing Machinery (ACM), Computer Professionals for Social Responsibility (CPSR), and has a certification in computer security (CISSP) from International Information Systems Security Certifications Consortium. He has been a fellow at the Berkman Center for Internet Law and Society, and remains a Berkman affiliate. He is also an FAA licensed pilot, although he doesn't get to fly much these days.

Garfinkel lives in Belmont with his wife and three children.

This document is located at http://simson.net/bio.html. Last updated August 30th, 2002.

Very impressive, it must feel good to be personally acquainted with someone so notable.

[Pagey]

FYI BUMP