Ask Slashdot: Best Way To Destroy Hard Drives?

First time accepted submitter THE_WELL_HUNG_OYSTER writes "I have 10-15 old hard drives I want to trash, some IDE and some SATA. Even if I still had IDE hardware, I don't want to wait several weeks to run DBAN on all of them. I could use a degausser, but they are prohibitively expensive. I could send them to a data destruction firm, but can they be trusted? What's the fastest, cheapest DIY solution?"

Comments

Hamer and punch

[plover]

If you're looking for fast production-line destruction, take a three pound hammer and punch. A punch driven through the aluminum plate covering the platter section, midway between the center spindle and the edge of the drive, down to the bottom of the case through the platters, will effectively destroy the disks. It will cheaply render the data unreadable to anyone who doesn't want to invest ten thousand dollars investigating the remains of the disks. You can crank through many disks per hour. A 3/8" bit in an electric drill would be similarly effective, and less labor intensive than a hammer, but slower.

Leaving the aluminum plate covering on the drive has the added advantage of containing the shards if the disk platters are made of glass. Even so, I'd wear leather gloves and use eye protection if I were physically destroying them this way.

But with 15 drives, it's just not that big of a job. Why make a big mess? Disassemble them. It takes about 10 minutes per drive, and it's both educational and fun. You can probably do it watching TV on the couch.

A miniature Torx driver set (T6-T9, available from Sears), a flat bladed screwdriver, a #2 Philips screwdriver, and a pocket knife is all I need to take most drives apart down to their components. Recover the voice coil driver magnets, they're always useful. Remove the circuit boards and recycle them as they were probably soldered with lead. Remove the platters from the spindles. To truly be rid of the data, you'll have to basically destroy the platters in a very hot fire. Heating them past their Curie point will completely destroy the data, leaving them totally unrecoverable; but that may require heat as high as 1500 degrees F. You won't get that on a stovetop.

Just zero it

[Reason58]

It is my understanding that there has never been a single proven recovery of a drive that was simply zeroed out. No silly "military grade" wipe software necessary.

Re:Just zero it

[daha]

With specialized equipment drives can be easily recovered when wiped by zeros. With even more sophisticated methods drives that have been written over several times can be recovered layer by layer.

Easily?!?! Layer by layer? Do you have personal experience recovering overwritten data in this fashion? If so, please let me know, my company would hire you in a heartbeat and you could name your price. This concept has been trashed over and over again on slashdot, and nothing has changed since the last time.

Think of the signal for a single bit on a platter like a digital Jackson Pollock painting using only two colors. One color represents a 1, the other color is a 0. Each write is a new splatter that gives the picture a new dominant color, but there are still some pixels left over from the previous splatters around the edges. Once the color of a pixel is set, it is set until you change it and you have no idea if the same color pixel next to it was written at the same time or not. You can just see that the overall color of the entire image is one or the other.

Now let's say, just for the sake of this discussion, that you were actually able to read these mythical "layers", or more appropriately, all the drops of the various splatters. Because this is a magnetic signal and not a physical layer of paint, you have no idea when any given pixel was written compared to the one next to it. There is no concept of a layer because the signals aren't stacked on top of each other, they are all next to each other. Now let's say that you have somehow managed to design and build the most sensitive magnetic read head ever conceived so that it is able to read the signal of every single molecule in the space that this bit occupies. That's great. Now you've determined that there were a bunch of 1's and 0's. Which order were they written in? Did that 1 from over to the left come before or after that 0 that you read from the lower right?

Assuming you got that figured out, now you need to get the next 7 bits just to make a byte. Did you get all 8 bits from the same write put together? Or did you screw one up because you got the ordering of your "layers" a little mixed up?

Now that you've got an entire byte reconstructed, you need to do the same with the other 511 bytes for the sector. Did you get all 4,096 bits for the sector correct for your "layer" of data? I'm a little skeptical...

Now go get the rest of your file, because it probably isn't all contained within a single 512 byte sector, and it may very well be written to different regions of the drive if it wasn't all written as a contiguous allocation. Depending on the file system and the size of the file, it's could be guaranteed that it is not contiguous - ext3 will be non-contiguous if it is larger than 6K.

Now that you have every bit recovered for a single file, did you get every bit correct? You're most likely in trouble if you screw up even a single bit and try to open it with the native application. LZ-based compression used for the file? It's almost sure to be busted as soon as you hit that bad bit and you won't be able to decompress anything beyond it. Different files have different tolerances, but unless you plan to look at everything with a hex editor, you're probably going to have a lot of trouble. Even something like a Word document (*.doc, not the *.docx) isn't going to be as easy as you think because the file does its own allocations of 64 bytes at a time within the file. If you did any edits, or have anything other than just plain text that is all the same font style, your text is no longer contiguous. If that Word document is using the new format (*.docx), then you out of luck because it is using a variant of LZ compression.

Oh, the file was a picture? No, still not always going to help you. Certain graphics file formats, like JPEG, do tolerate some corruption of the data (depending on where the corruption shows up), but some are just as fragile as a compressed data file.

Now repeat this for every file until you find files that are actually valuable to you. The amount of effort needed to reconstruct anything that has been overwritten far exceeds the value of whatever data it was.

Re:How I've done it in the past...

[danbuter]

You can buy muriatic acid in just about any hardware store. It's basically hydrochloric acid.

Re:Screwdriver

[Anonymous Coward]

I always take them apart for the free magnets inside.

Open them up and salvage the magnets

[SensitiveMale]

Very powerful magnets in the drives. Open them up, take out the magnets, and throw away the drives. If you are really paranoid, pop the discs out. But definitely salvage the magnets. They come in handy.

DBAN is unnecessary.

[rollingcalf]

One pass with zeroes or random data over the whole drive is sufficient, unless you expect that a large government agency is going to open up the hard drives and spend millions of dollars to attempt to recover the data (and even they might be unable to get at the overwritten data. See http://www.nber.org/sys-admin/overwritten-data-guttman.html).

With dd if=/dev/zero of=/dev/sdb you can wipe all the hard drives in a weekend.

Re:oven

[SCPRedMage]

In the Air Force, we had EOD take care of the problem.

With C4.

And I'm not making this up. The drives weren't working, so we couldn't just wipe them, and EOD was bored and had explosives...

Re:oven

[JWSmythe]

    Well, for those of us living in the civilian world, C4 is hard to get our hands on.

    Thermite, on the other hand, can be made rather easily from things around the house. A file or grinder, a bit of the appropriate metals, and an ignition source. Be sure that your "Member of the Overkill Club" card is up to date, and you're all set. 5 pounds of thermite vs 1 hard drive sounds just about right. Well, right through the drive, and the table, and the concrete below. :)

    Actually, thermite may be the better choice anyways, unless you want to notify everyone for miles that you're using C4. :) It has lots of hot, and not much bang. Well, especially compared to C4.

    And remember kids, don't try this at home. It's a really really (really) good way to burn down your house, get the police called by a neighbor, and/or be charged with arson and building explosives. Some law enforcement folks don't look upon such things as lightly as they used to.

Re:oven

[MrAngryForNoReason]

so you could just walk in (hold drives very tightly), and keep them in the machine for a while.

Not the best idea as the drives would be ripped out of your hand and fly towards the machine at a high enough velocity to kill anyone in the way. Oh and you would probably destroy the MRI in the process.

There is a very good reason why you don't take metal anywhere near an MRI machine.