Ten Ways To Destroy a Hard Disk

Barence writes "Following his blog last week about the homemade hard disk destroyer, Bustadrive, Mike Jennings was deluged with comments from readers, both on the blog and here on Slashdot. Most seemed to like the product, but also offered up far more innovative and madcap methods of hard disk destruction, with a wide range of implements used — household and otherwise. In this follow-up post, he rounds up the best of an imaginative bunch of hard disk destruction methods."

Magnesium

[Hubbell]

If you have the harddisk out of the shell, buy 1 package of sparklers, if it's inside it, get around 4-5 packages (the metal sticks with grayshit on them)

Strip the grayshit (magnesium normally, if its something else it probably wont work as well through the case) and crush it into a powder off of all sparklers but 1, you can strip the last one down to about an inch or so from the tip. Pile it all on the harddisk/shell, light the sparkler tip that's left, insert into the pile, and other than it appearing as though the sun is arm's length in front of you for 5-10 seconds, anything underneath shall be melted/vaporized due to the white hot heat released. I've melted through steel grills at my local beach at night this way before, around 11pm 1 package of sparklers prepared this way lit up the local beach on long island sound for about a mile in all directions as if it was daytime.

The Actual List ...

[neonprimetime]

1 - The classic hammer
2 - "What's wrong with an angle grinder?"
3 - The average welding torch
4 - weaponry, from 12-gauge shotguns to high velocity rifles
5 - Science fans will be pleased to see an electromagnet on the list
6 - use a drill
7 - Hard disk platters are generally made from aluminium, which melts at 660.32C
8 - Electric log splitters
9 - An industrial shredder
10 - Finally, another method that scores valuable points for science: Thermite

Re:Magnesium

[Hubbell]

How exactly would I get a darwin award for something which is nonexplosive? Magnesium merely burns white hot until it's all gone.

Re:How about: Write zeros to the disk?

[Anonymous Coward]

No he can not. There is not a single data recovery company in the whole wide world advertising this capability and there isn't a single lawsuit in which data from an overwritten disk has been used as evidence. Data recovery from overwritten hard disks is BULLSHIT.

Re:How about: Write zeros to the disk?

[bmo]

Who the hell modded this informative?

It's perpetuating a myth.

Even Guttman says that with modern hard disks it's impossible to retrieve data once overwritten.

http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html [auckland.ac.nz]

Epilogue
In the time since this paper was published, some people have treated the 35-pass overwrite technique described in it more as a kind of voodoo incantation to banish evil spirits than the result of a technical analysis of drive encoding techniques. As a result, they advocate applying the voodoo to PRML and EPRML drives even though it will have no more effect than a simple scrubbing with random data. In fact performing the full 35-pass overwrite is pointless for any drive since it targets a blend of scenarios involving all types of (normally-used) encoding technology, which covers everything back to 30+-year-old MFM methods (if you don't understand that statement, re-read the paper). If you're using a drive which uses encoding technology X, you only need to perform the passes specific to X, and you never need to perform all 35 passes. For any modern PRML/EPRML drive, a few passes of random scrubbing is the best you can do. As the paper says, "A good scrubbing with random data will do about as well as can be expected". This was true in 1996, and is still true now.

Looking at this from the other point of view, with the ever-increasing data density on disk platters and a corresponding reduction in feature size and use of exotic techniques to record data on the medium, it's unlikely that anything can be recovered from any recent drive except perhaps a single level via basic error-cancelling techniques. In particular the drives in use at the time that this paper was originally written have mostly fallen out of use, so the methods that applied specifically to the older, lower-density technology don't apply any more. Conversely, with modern high-density drives, even if you've got 10KB of sensitive data on a drive and can't erase it with 100% certainty, the chances of an adversary being able to find the erased traces of that 10KB in 80GB of other erased traces are close to zero.

Also:

http://sansforensics.wordpress.com/2009/01/15/overwriting-hard-drive-data/ [wordpress.com]

What this means

The other overwrite patterns actually produced results as low as 36.08% (+/- 0.24). Being that the distribution is based on a binomial choice, the chance of guessing the prior value is 50%. That is, if you toss a coin, you have a 50% chance of correctly choosing the value. In many instances, using a MFM to determine the prior value written to the hard drive was less successful than a simple coin toss.

The purpose of this paper was a categorical settlement to the controversy surrounding the misconceptions involving the belief that data can be recovered following a wipe procedure. This study has demonstrated that correctly wiped data cannot reasonably be retrieved even if it is of a small size or found only over small parts of the hard drive. Not even with the use of a MFM or other known methods. The belief that a tool can be developed to retrieve gigabytes or terabytes of information from a wiped drive is in error.

--
BMO

Re:The most fun...

[impaledsunset]

Trying to destruct a drive while the plates are spinning and the disk is open can be dangerous. I've done it a few times, but recently there are some manufacturers that make the plates from glass, and the glass can easily be crused if you do something to the plates while they're spinning, or you spin them too fast. I knew a kid who had been injured by hitting a glass plate of a hard drive while it was spinning.

Re:How about: Write zeros to the disk?

[Lord Ender]

You are almost right, but not entirely. Some drive firmware (as I understand it) will detect failing sectors of the disk and mark them as "bad." Your software won't even see them, as this is done at the firmware level. This means your data will still be there on the disk, even after a zero-write.

Re:How about: Write zeros to the disk?

[prockcore]

That and he's assuming that the harddrive actually writes out ones and zeroes. That's not how it works.

The harddrive stores information on the disk as a constant magnetic field, the only "information" on the disk is the polarity of the magnetic field. So a "bit" on disk is positive, or it is negative.

The harddrive stores information using flux reversal. A 1 is a flux reversal, a 0 is no change. So 1001110 is stored as +---+-++. Switching polarity is considered a 1, not switching is a 0. 1001110 could also be represented as -+++-+--, it all depends on the current polarity when the data is written. The harddrive uses RLL encoding, so 1001110 is actually written out as 01000010000100.

Also, you have to read the entire sector, since the data is xored together before it is RLL encoded. A single byte in a sector is garbage unless you xor it with all the bytes after it in the sector.

Re:How about: Write zeros to the disk?

[lgw]

Government protocol for destruction of a drive that has ever held secret data is to shred the drive until the pieces pass through a 1 mm sieve. No amount of "passes" will erase data on sectors that the drive firmware has marked "bad". 1 pass with random data is adequate to prevent recovery (on a GMR drive, and probably on any post-MFM drive), but only for those sectors the HHD firmware is still willing to write to.

In practice, the government often just sells the computer without taking any steps to delete the data. But hey, that's government for you.

My method of HDD disposal

[kheldan]

1. Remove drive from computer
2. Dismantle drive, remove platters and magnets
3. Use magnets for interesting things
4. Either: Use platters for interesting things, or: Destroy platters (bending them up works well)
Cost: essentially nothing.

Re:How about: Write zeros to the disk?

[Anonymous Coward]

Zeros are much faster. /dev/urandom is slow. /dev/random is glacial.