'Cleaned' hard drives reveal secrets

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

[vannrox]

'Cleaned' hard drives reveal secrets

14:32 16 January 03

Will Knight

Discarded and recycled computer drives can reveal financial and personal information even when apparently wiped clean, MIT researchers have found.

Simson Garfinkel and Abhi Shelat, graduate students at the Massachusetts Institute of Technology, analysed 158 second hand hard drives bought over the internet between November 2000 and August 2002. They were able to recover over 6000 credit card numbers, as well as email messages and pornographic images.

The pair wrote a program to scour the disk drives for any trace of credit card information. They found card numbers on 42 drives of the drives they bought.

One drive had previously been used in an ATM cash machine and contained 2868 different numbers, as well as account and transaction information. Another drive contained a credit card number within a cached web page.

Privacy failure

Much of the information the researchers found had been "deleted" before the disks were sold. But simply deleting a file with most computer operating systems does not remove it from the hard drive, it only removes a tag pointing to the file.

Furthermore, even re-formatting the disk does not properly remove the contents of files.

"Most techniques that people use to assure information privacy fail when data storage equipment is sold onto the secondary market," the researchers write in an article to appear in the IEEE magazine Security and Privacy. "The results of even this limited initial analysis indicate that there are no standard practices in the industry [for sanitizing disks]."

Data remembrance

The study, entitled Remembrance of data passed: a study of disk sanitization practices, concludes that overwriting disks with random data, preferably more than once, should be sufficient to wipe them clean. But only 12 per cent of the drives they bought had been cleaned in this way.

They also note that it may be possible to recover information even when it has been overwritten with random data. This would require the use of magnetic force microscopy to measure the subtle magnetic changes that occur during each overwrite.

Finally, the researchers add that cryptographic file systems would improve hard drive security by requiring authentication before revealing data. But they say this type of system is very rarely used.

14:32 16 January 03

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[azhenfud]

I believe Norton has a utility to clean wipe a disk by wiping the free space or the entire disk. Either method, the user is allowed to choose the type of wiping, standard or government secure.

http://howto.lycos.com/lycos/step/1,,10+59+26168+25621+19937,00.html

[steve-b]

One of the drives came from an ATM machine, and the vast majority of card numbers came from that drive.

Today's Statistics 101 lesson: This is an example of why the median is often more meaningful than the mean.

[js1138]

My checkbook balance is on my computer. Hard for anyone to get in too much trouble with that!

As Shakespeare said, He who steals my purse, steals trash.

[steve-b]

I wonder what the US Gov does to dispose of "classified" hard drives?

From what I've heard, it involves thermite....

[HoustonCurmudgeon]

Oh ok. So that means the average hard drive has only about 28 credit card numbers on it. That's more like it.

I assume you have dug a hole and just like being there? If one hard drive had 2800+ might one or two others have a high number? They don't list the number on each, just the total and the worst. Is anything gained by them not telling the truth? Can you see any reason why they might do that?

BTW I would not have responded at all, save that people who use "Hmmmm" just bug the hell out of me, as they seem to imply something they are unable or unwilling to say. Hmmmmmmmmm!

[qwas]

AbsoluteShield File Shredder is a free program that takes care of that problem. http://www.sys-shield.com/fileshredder.htm

[azhenfud]

Yeah, mine's all 0's & 1's too....

[spetznaz]

Amen to that!

That is a way of totally ensuring no one will access anything from a hard drive.

[aristeides]

So what's happened to the Clinton White House's computers?

[strela]

From what I've heard, it involves thermite

You are correct, in some cases. A thermite grenade or two can certainly render a hard drive into molten slag. And they're fun to watch.

[Ides of March]

I wonder what the US Gov does to dispose of "classified" hard drives?

Not a problem.

Their computers are usually stolen before it's time to dispose of them.

Beware.

[Fiddlstix]

To the best of my knowledge, a LLF will clean everything off the disk.
(Low Level Format)

[aShepard]

I wonder what the US Gov does to dispose of "classified" hard drives? I sort of imagine it involves fire, or some equivalent of your heavy duty hammer

Nope, they send all used hard drives to this place in China: Crintoons Cowectibles.

[aShepard]

I wonder what the US Gov does to dispose of "classified" hard drives? I sort of imagine it involves fire, or some equivalent of your heavy duty hammer

Nope, they send all used hard drives to this place in China: Crintoons Cowectibles.

[Apple Pan Dowdy]

"Laugh if you want, but I love it when he sings "Bridge Over Troubled Water"."

Or maybe when he sings: Bride Over Troubled Waiter???

[VeritatisSplendor]

I remember Simson well from MIT in the early 80's. He was annoying and hyperactive, but no more so than hundreds of other MIT nerds (including me), and fit in fine. We were both on the staff of The Tech, MIT's student newspaper. When he started he was an absolutely terrible writer, but he contributed so much content that they let him keep writing, and after a couple of prolific years he became pretty good. He was a medium-sized kid with one of those frizzy "Jewish Afros". Definitely the type to have been a Ritalin candidate when younger -- you're right, the world needs 'em. (That, IMO, is why autism and related disorders haven't been bred out of the species -- you'd have a lot fewer brilliant nerds.)

I like the camp story. Reminds me of my son when he was 8 (or me when I was 8).

[usastandsunited]

I assume you have dug a hole and just like being there?

Nah, I just like seeing you get irritated. Hmmmmmm.
Lighten up. You win. This is a trival issue. Get stressed over more important things if you must be irritated with something.

[Lael]

It can be used on a day to day basis to delete one file at a time, not a whole diskDo a Google search for "ERASER". It is a powerful erase program from Finland, currently being maintained by someone in Ireland.

It is freeware, and has a hoast of options. If you Right Click on the drive symbol, you will notice "erase unused space"...use it!

For added security, remember to turn off Virtual Memory...this ensures that the Swap File is erased as well.

Good luck!

[Search4Truth]

http://www.evidence-eliminator.com/

[gridlock]

That's why I defrag it after I've filled it.

But I'm just trying to avoid problems with stuff popping up that I don't want. Not high security or anything. For high security, I prefer the sledge-o-matic approach to hard drives.