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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?

#71

Post by robocat »

wheresmyusern wrote: post #52

even if you drill a hole in the drive, data can still be recovered from it. anything that leaves large pieces of drive intact really isnt ideal. over the years i had collected dozens of platters from both myself and other people. for some reason, when i was younger i was obsessed with collecting hard drive magnets and also smart enough to understand that i probably shouldnt throw the platters away. so a few years ago…

Boiling off the rare earth surfaces and breathing them in could be a health risk?

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

#72

Post by OliverJones »

HIPAA - regulated health data requires physical destruction of retired hard drives. Usually this is done in sight of a video camera. The operator shows the drive's serial number to the camera and then drops it into the grinder.

CMS (Centers for Medicare and Medicaid Services) can require proof of destruction. That video does it.

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

#73

Post by topspin »

Symbiote wrote: post #20
nilram wrote: post #11

A friend uses a saws-all (or something of that ilk) and cuts them in half. I'm figuring on taking my old drives to him for that treatment. I don't want to resell them and have a casual snooper recover my data, and I'm not of enough interest for anyone to piece the halves together.

What's the risk from simply writing over the drives with zeros, and sticking them in the electronics recycling? I don't think anything I or my employer has would be worth the effort to recover.

This is what NIST says about it[1]:

    Advancing technology has created a situation that has altered previously held best practices
    regarding magnetic disk type storage media. Basically the change in track density and the
    related changes in the storage medium have created a situation where the acts of clearing and
    purging the media have converged. That is, for ATA disk drives manufactured after 2001
    (over 15 GB) clearing by overwriting the media once is adequate to protect the media from
    both keyboard and laboratory attack.
That's an elaborate way of saying that zeroing a healthy modern disk is sufficient. No need to break out the crucible or jackhammers. If you really need to indulge your paranoia then use some wiping system that does multiple overwrites with random data. It's not necessary, but at least you won't put your eye out.

[1] http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublic...

If the device isn't healthy and can't zero all of the media then you will need to resort to physical destruction.

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

#75

Post by EvanAnderson »

syshum wrote: post #67
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.

That was my "take away" to "playing with magnets around spinning rust media". It has nothing to do with my attitude toward data backup, or with playing with magnets in general. I have no desire to induce further failures in any other spinning-rust media.

It was a failure in following disciplined practices, in this instance, and it caused me monetary loss. It was a good lesson. I am happy with my attitude toward data security and data loss, and it's certainly not codified in the statement "never play with magnets".

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

#76

Post by EvanAnderson »

syshum wrote: post #70
EvanAnderson wrote: post #36

Earlier quoted context omitted.

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 magnet…

I've only had the opportunity to tear down a few consumer drives in the last few years. I haven't seen inside an enterprise-class drive in a few years. (I've stopped dealing with hardware directly for my Customers, and I haven't purchased much hardware for personal use over the last few years.)

I've found scavenged hard drive magnets to be very useful for odd jobs. One served several years holding up the fallen head-liner over the drivers seat in one of my crappier cars.

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

#77

Post by ben-schaaf »

Spooky23 wrote: post #47
readams wrote: post #5

Earlier quoted context omitted.

Normally you'd want to throw the remains into a volcano but I guess if you feel safe just throwing it away then you do you.

You jest, but jackass security people would probably be dissatisfied that your PII might be accessible to some alien race when after the earth explodes in 5 billion years and some remanent of data is somehow recoverable from an asteroid made of cooled lava. I recall one datacenter consolidation project where the hard drives from decommissioned servers were zapped with a degaussing device, shredded, and then somebody…

There's a great defcon talk exploring different methods to completely destroy a drive: https://www.youtube.com/watch?v=-bpX8YvNg6Y.

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

#78

Post by PuffinBlue »

Spooky23 wrote: post #47
readams wrote: post #5

Earlier quoted context omitted.

Normally you'd want to throw the remains into a volcano but I guess if you feel safe just throwing it away then you do you.

You jest, but jackass security people would probably be dissatisfied that your PII might be accessible to some alien race when after the earth explodes in 5 billion years and some remanent of data is somehow recoverable from an asteroid made of cooled lava. I recall one datacenter consolidation project where the hard drives from decommissioned servers were zapped with a degaussing device, shredded, and then somebody…

I failed an audit once because the inspection team managed to recover data from the information encoded on the event horizon of a nearby black hole.

Can't be too careful nowadays.

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

#79

Post by kosma »

wheresmyusern wrote: post #52

even if you drill a hole in the drive, data can still be recovered from it. anything that leaves large pieces of drive intact really isnt ideal. over the years i had collected dozens of platters from both myself and other people. for some reason, when i was younger i was obsessed with collecting hard drive magnets and also smart enough to understand that i probably shouldnt throw the platters away. so a few years ago…

You don't even need to melt them. Just reaching the Curie point should be enough.

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

#80

Post by darkmighty »

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

> such that loss of a single bit means the original key is unrecoverable

That can't be right (I don't know anything about this though). If you control the data (with a non-interactive non-destructive decryption process), a loss of a single bit just means you have to test two possible keys. In terms of brute forcing, the security is the same per number of bits lost. The benefit of using a large key would be that if you lose a certain fraction of your key (say 10%), then that would correspond to more bits (as long as you erase 128 or more bits you'd be fine).

Also beware of key stretching, use it only when absolutely necessary. Key stretching doesn't modify the ratio of work necessary for your encryption/decryption vs the work necessary for brute forcing -- i.e. it doesn't improve the security factor. You're essentially doing an economic defense vs a mathematical one, and hoping that computers won't improve and your attacker isn't willing to spend much relative to what you spent.

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