How secure is merely discarding (TRIMing) all of a SSD's blocks?
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How secure is merely discarding (TRIMing) all of a SSD's blocks?
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Re: How secure is merely discarding (TRIMing) all of a SSD's blocks?
#2> Flash storage, unlike traditional hard drives, can really be completely and irrecoverably erased, with no lingering magnetic ghosts that a sufficiently determined person could in theory reconstruct.
I think people vastly overestimate the possibility to recover any data from a wiped HDD.
See for example this article by SANS [1]. To recover a single bit you have a better chance of flipping a coin to see if the bit was a zero or a one then you have when you are actually trying to reconstruct it with lab equipment.
[1] https://web.archive.org/web/20140621130410/https://digital-f...
Re: How secure is merely discarding (TRIMing) all of a SSD's blocks?
#3Super interested in this and would love to hear about some techniques. Used to work at a HealthTech co. We had an “appliance” that we’d send to doctor offices to integrate with other diagnostic machines on the network.
Sometimes we would send out new ones to replace the old. When we got the old ones back, it was always unclear how to purge and recommission SSD/NVME drives.
My best attempt was using GNU shred, but it wasn’t recommended for flash-based storage back then.
Re: How secure is merely discarding (TRIMing) all of a SSD's blocks?
#4Also see:
https://wiki.archlinux.org/title/Solid_state_drive/Memory_ce...
https://www.usenix.org/events/fast11/tech/full_papers/Wei.pd...
Edit: see section 3.2.2 in the PDF (and the corresponding table 2):
> In most cases, overwriting the entire disk twice was sufficient to sanitize the disk, regardless of the previous state of the drive. There were three exceptions: about 1% (1 GB) of the data remained on Drive A after twenty passes
This is about normal overwriting, however. The fastest random overwriting program on Linux I know of is `shred`
Re: How secure is merely discarding (TRIMing) all of a SSD's blocks?
#5Or you encrypt the entire drive. Then the secure erasure is a matter of throwing away the keys, and you don't have to bother with thinking through your threat model.
Re: How secure is merely discarding (TRIMing) all of a SSD's blocks?
#6This is why you always want to use full disk encryption (FDE). Then it doesn't really matter whether some blocks are recoverable after TRIM. It also doesn't really matter whether the Secure Delete function works. It also doesn't matter whether the very expensive security-buzzword-compliant secure deletion snakeoil software really works.
Also, TRIM is only possible with drives that are still in working order. Very often you can't TRIM or secure delete a drive that is defective and returned by RMA. In that case you either need a very expensive no-disk-return support contract. Or you just use FDE.
Re: How secure is merely discarding (TRIMing) all of a SSD's blocks?
#7Super interested in this and would love to hear about some techniques. Used to work at a HealthTech co. We had an “appliance” that we’d send to doctor offices to integrate with other diagnostic machines on the network. Sometimes we would send out new ones to replace the old. When we got the old ones back, it was always unclear how to purge and recommission SSD/NVME drives. My best attempt was using GNU shred, but it…
The only proper way of disposal is physical destruction, preferrably on site and under observation of inhouse staff. There are contractors you can hire in those: https://shredsupply.com/hard-drive-shredding-trucks/ (no relation, just arbitrary google hit).
I'm also unsure as to why you are getting drives back at all, any of your customers should not have any kinds of storage devices leave their site intact. At least that is the standard over here in Europe for healthcare and other industries dealing with sensitive data.
Re: How secure is merely discarding (TRIMing) all of a SSD's blocks?
#8> Flash storage, unlike traditional hard drives, can really be completely and irrecoverably erased, with no lingering magnetic ghosts that a sufficiently determined person could in theory reconstruct. I think people vastly overestimate the possibility to recover any data from a wiped HDD. See for example this article by SANS [1]. To recover a single bit you have a better chance of flipping a coin to see if the bit wa…
This can't be true. Any method must be at least as good as a coin toss. If it's worse you can just bit flip the result and end up better than the coin.
Re: How secure is merely discarding (TRIMing) all of a SSD's blocks?
#9Super interested in this and would love to hear about some techniques. Used to work at a HealthTech co. We had an “appliance” that we’d send to doctor offices to integrate with other diagnostic machines on the network. Sometimes we would send out new ones to replace the old. When we got the old ones back, it was always unclear how to purge and recommission SSD/NVME drives. My best attempt was using GNU shred, but it…
In addition to the sibling comment, I'm surprised that there was no mention of FDE.
Re: How secure is merely discarding (TRIMing) all of a SSD's blocks?
#10HDPARM secure-erase uses the OPAL standard which ensures unused bad blocks, that the drive normally ignores, are erased too. TRIMMING only cleared blocks normally accessible for reading/writing. It’s not as low level…
But as someone has mentioned you can just enable encryption and forget the keys…most all SSDs are encrypting from new…user and master keys just have to be set.