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Can I erase sensitive data on an old hard drive with Neodymium Magnets?

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Re: Can I erase sensitive data on an old hard drive with Neodymium Magnets?

#61

Post by oldandtired »

There are techniques used to recover previously erased information on HDDs. These techniques have been available since the 90's. The best way to make it unrecoverable is to melt the disks by the use of whatever techniques you have available, including ox-acetylene torches (the favoured method for the company at the time I was working for them), putting into a furnace (as suggest by others here), etc.

The problem with erasure is that there is residual amounts of magnetic fields that can be picked up by the right equipment. In the day, it was reported that they had success with recovery of information that had been overwritten by 8 - 10 times. It just took a lot of patience to do so. Those who want to recover this information will have that patience.

Re: Can I erase sensitive data on an old hard drive with Neodymium Magnets?

#62

Post by rgbrenner »

keithpeter wrote: post #26
tscs37 wrote: post #4

If you want to get rid of a harddrive with sensitive data I would first suggest that one gets familiar with the thought of not being able to sell it as used. Personally for my drives, I use Boot and Nuke to erase the drive three times, first with zeroes, then with random data, then with zeroes again. After that I disassemble the drive, put a strong magnet over each platter, shredder the drive into almost powder, burn…

How about whole disk encryption? When it is time to move on, one simply forgets the passphrase and reformats the drive. Seriously: that is what I'm doing with ssd drives. Anyone know of any issues?

a lot of ssds already encrypt the data using aes... and you can send a command to the drive telling it to erase the key.

better because it's harder to bruteforce an aes key than a passphrase.

Re: Can I erase sensitive data on an old hard drive with Neodymium Magnets?

#63

Post by allenz »

magnat wrote: post #3

Hard disks are surprisingly hard to destroy on-demand. There was a DEF CON 23 talk [1] exploring ways to quickly wipe your servers in situ using physical methods. [1] https://www.youtube.com/watch?v=-bpX8YvNg6Y

Entertaining talk, but the best method is to discard the key for your fully encrypted disk. It's 2017, all your disks use FDE, right?

Re: Can I erase sensitive data on an old hard drive with Neodymium Magnets?

#64

Post by forapurpose »

keithpeter wrote: post #26
tscs37 wrote: post #4

If you want to get rid of a harddrive with sensitive data I would first suggest that one gets familiar with the thought of not being able to sell it as used. Personally for my drives, I use Boot and Nuke to erase the drive three times, first with zeroes, then with random data, then with zeroes again. After that I disassemble the drive, put a strong magnet over each platter, shredder the drive into almost powder, burn…

How about whole disk encryption? When it is time to move on, one simply forgets the passphrase and reformats the drive. Seriously: that is what I'm doing with ssd drives. Anyone know of any issues?

Self-encrypting drives (SEDs) have this function built in:

1. Everything stored on the drive is always encrypted when at rest.

2. The drive has some sort of firmware, memory and microprocessor that stores a key and en/de-crypts data in transit to/from storage.

3. To 'erase' the drive, the SED simply erases the key.

Of course there are many potential flaws in implementation, but conceptually it's simple. And as with most drive encryption solutions, the fatal flaw is that the data is available if the computer is on or asleep, which means that for most users the security is disabled 99% of the time (but that problem doesn't apply to drive wiping).

AFAIK: Many common drives have SED functionality. Until the user "locks" the drive, the data is en/decrypted invisibly to the user and system. Locking the drive creates a passphrase and a pre-boot environment for authentication. Locking the drive requires an OS-level utility. Opal by TCG (the same people who provide the TPM spec) is the common standard.

Re: Can I erase sensitive data on an old hard drive with Neodymium Magnets?

#65

Post by rgbrenner »

tfha wrote: post #46

Best method is to use LUKs and then wipe the master key. Luks has a forensic stretching technique to take a 32 byte master key and stretch it to 1 MiB, such that loss of a single bit means the original key is unrecoverable. That really helps you wipe things like SSDs which can copy and migrate data, and make it hard to be certain you destroyed a sector

most ssds already encrypt data with aes.. you can just send a command to the drive telling it to erase the key.

Re: Can I erase sensitive data on an old hard drive with Neodymium Magnets?

#67

Post by syshum »

EvanAnderson wrote: post #17

Here's my anecdote: In 2006, while sitting at my desk playing a video on the hard disk drive of my Thinkpad T22, I held a single neodymium magnet (harvested from an old hard disk drive) about 6 inches from the left side of the unit (where the ~40GB-ish Travelstar 2.5" PATA disk was located). The video froze, Windows XP blue-screened, and the hard disk drive started emitting a ~10Khz whine. I jerked my hand away from…

>I won't ever play with neodymium magnets around spinning rust media again.

That is your take away? Not that "I ensure all my data is backed up using the 3-2-1 Method at a minimum" it is "never play with magnets"?????? Really?

People never cease to amaze me when it comes to data security.

Re: Can I erase sensitive data on an old hard drive with Neodymium Magnets?

#68

Post by Waterluvian »

dpedu wrote: post #32
EvanAnderson wrote: post #17

Here's my anecdote: In 2006, while sitting at my desk playing a video on the hard disk drive of my Thinkpad T22, I held a single neodymium magnet (harvested from an old hard disk drive) about 6 inches from the left side of the unit (where the ~40GB-ish Travelstar 2.5" PATA disk was located). The video froze, Windows XP blue-screened, and the hard disk drive started emitting a ~10Khz whine. I jerked my hand away from…

From 6 inches away? Unless this was a hockey-puck sized magnet I'm calling it a coincidence. > (harvested from an old hard disk drive) Okay, this is making even less sense. "Hard drive magnets", in a drive, are millimeters from the spinning platters. I refuse to believe that the same magnet, moved 6 inches away from the computer caused catastrophic damage.

I stack hard drives and they keep working.

Re: Can I erase sensitive data on an old hard drive with Neodymium Magnets?

#69

Post by gruturo »

dboreham wrote: post #18

No. You need to cast it into the fires of Mordor. Or something similar.

Something similar is indeed the right answer here. You have to take the material above its curie temperature (https://en.m.wikipedia.org/wiki/Curie_temperature) and then according to physics all preexisting magnetic information is lost.

Re: Can I erase sensitive data on an old hard drive with Neodymium Magnets?

#70

Post by syshum »

EvanAnderson wrote: post #36
dpedu wrote: post #32

Earlier quoted context omitted.

From 6 inches away? Unless this was a hockey-puck sized magnet I'm calling it a coincidence. > (harvested from an old hard disk drive) Okay, this is making even less sense. "Hard drive magnets", in a drive, are millimeters from the spinning platters. I refuse to believe that the same magnet, moved 6 inches away from the computer caused catastrophic damage.

I will definitely concede that the 6" number may be an incorrect memory. It certainly may have been closer, but it wasn't right on top of the unit. If it was a coincidence it was certainly well-timed. I don't have the Thinkpad anymore, but I do still have some 2.5" PATA drives. It might be interesting to test this and make a video. Here's a picture of the magnet in question (it holds stuff to my refrigerator now), w/…

>> They are physically larger (substantially thicker) than the ones I've pulled from newer drives.

Not really, they look very close in size to current Enterprise Drives (https://imgur.com/2HjuuKM), Of course I have removed the Metal backing plate from mine

Now consumer drives do have smaller magnets (that is one way to save cost)

Here is a photo of the 4 styles of magnets I still personally have, the smaller magnets are either out of consumer drives and 2.5in drives manufactured in the last 7 years https://imgur.com/59XjVPm

And just for fun a small assortment of my collection because why not

https://imgur.com/bW6ycRI

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