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Re:Rowhammer-like attack on SSDs can provide root privileges... by dmitrygr on Wednesday August 16, 2017 @03:31PM (#15030445)
This is idiocy. Modern drives AES encrypt data to provide whitening. You do not have the key nor do you set it or care for it. Without it you'll not be able to pull this off. Their attack will only work on very old SSDs that do not whiten data. All modern MLC/TLC chips REQUIRE whitening and AES is often used since it whitens well and is fast.
Re:Rowhammer-like attack on SSDs can provide root privileges... by burkaman on Wednesday August 16, 2017 @03:35PM (#15030478)
This would be a much more productive comment if you took out the first sentence.
Re:Rowhammer-like attack on SSDs can provide root privileges... by wtallis on Wednesday August 16, 2017 @04:44PM (#15031223)
Some mention needs to be made of how unreasonably sensationalized the article is.
Re:Rowhammer-like attack on SSDs can provide root privileges... by burkaman on Wednesday August 16, 2017 @05:12PM (#15031417)
It doesn't seem sensationalized to me, but I don't know much about the domain. Other ways to phrase a comment are "This isn't very dangerous in practice" or "This won't work on modern hardware" or "The risk in this article is exaggerated".
Re:Rowhammer-like attack on SSDs can provide root privileges... by wtallis on Wednesday August 16, 2017 @05:47PM (#15031657)
Trust me, it's sensationalized to the point of being highly irresponsible reporting. This research first made the rounds early this year, and I analyzed it in depth. Properly explaining all the caveats behind this "attack" requires more space than this entire article.

Among other things, making a successful attack would require sufficient privilege level to bypass all layers of read caches (and probably also all write caches), a target SSD that doesn't use modern 3D NAND, and intimate knowledge of the internals of the SSD controller and firmware, potentially up to the internal state of the LFSR or AES used to scramble data before it is written to the flash.

There's interesting stuff in this research; it highlights aspects of the unreliability of flash memory that I haven't previously seen emphasized so clearly. But since everything about SSD design already assumes that the flash memory is thoroughly unreliable and untrustworthy, these corner cases don't rise to the level of a real-world vulnerability.

Re:Rowhammer-like attack on SSDs can provide root privileges... by jontro on Wednesday August 16, 2017 @07:38PM (#15032331)
This is the paper https://pdfs.semanticscholar.org/b9bc/a3c9f531002854af48de12... that this is based on. They claim to be able to extract the key using hdparm. Afaik that needs elevated permissions to run.
Re:Rowhammer-like attack on SSDs can provide root privileges... by wtallis on Wednesday August 16, 2017 @07:52PM (#15032422)
> They claim to be able to extract the key using hdparm.

No, they claim only to be able to use hdparm to extract the logical block address at which a file is stored. Whether that gives you any useful information is entirely dependent on the internals of the SSD.

Re:Rowhammer-like attack on SSDs can provide root privileges... by wyager on Wednesday August 16, 2017 @05:16PM (#15031442)
I think the meme of "never say anything harsh lest you make someone sad" is counterproductive. It's very important to productive discourse that people are able to express the entire range of intensity with which they may feel an opinion. In particular, if something is stupid you should be able to say so.
Re:Rowhammer-like attack on SSDs can provide root privileges... by burkaman on Wednesday August 16, 2017 @06:08PM (#15031792)
You can be as harsh as you need without being a dick. Just address the content and what's wrong with it, not how stupid you think the author is. On the very rare occasion that it's useful to talk about someone's intelligence, you should say more than "you're an idiot".
Re:Rowhammer-like attack on SSDs can provide root privileges... by jtbayly on Wednesday August 16, 2017 @06:26PM (#15031885)
Maybe you're not aware that in English there is a difference between saying "You're an idiot." and "This is idiocy."
Re:Rowhammer-like attack on SSDs can provide root privileges... by burkaman on Wednesday August 16, 2017 @09:50PM (#15033090)
I don't want to get into an argument about definitions or semantics. Those phrases are different, but they come across similarly to me and many others, at least in this context. That's really all that matters in a casual discussion like this.

I understand not everyone will have the same reaction. I don't pretend to speak for everyone, but I suspect I speak for the majority.

Re:Rowhammer-like attack on SSDs can provide root privileges... by rasz on Wednesday August 16, 2017 @10:44PM (#15033385)
Lying in your paper is being a dick

>Author here, I would like to set the record straight.

>We do not claim to have an attack on SSDs.

but in the paper:

>>"We assume that the victim system runs a filesystem on top of MLC NAND flash-based SSD."

Re:Rowhammer-like attack on SSDs can provide root privileges... by burkaman on Wednesday August 16, 2017 @11:02PM (#15033474)
You're right. If the author lied, say that. Don't just say "idiocy".

Also, those sentences aren't contradictory. "Note that this result does not depend on whether you are using an SSD, a disk, or any other storage for your filesystem." Meaning the attack might apply to someone using an SSD, but the SSD has nothing to do with the vulnerability. It is useful to precisely define a model case in the paper so your results can be easily reproduced, even if some details are not required to demonstrate the vulnerability.

Re:Rowhammer-like attack on SSDs can provide root privileges... by CountSessine on Wednesday August 16, 2017 @06:07PM (#15031782)
Why is intensity at all relevant? Are ad-hominem attacks fair-play? The original poster called this 'idiocy' - is that an engineering term? This isn't about trying not to "make someone sad" - the OP has gone much further than "making someone sad".
Re:Rowhammer-like attack on SSDs can provide root privileges... by wyager on Wednesday August 16, 2017 @07:46PM (#15032382)
Because "I disagree with this" is semantically different from "this is stupid". They communicate different ideas. You can disagree with something without thinking it's stupid. A reader can and probably should react differently to a post being intelligent, but wrong, versus being just plain idiotic.

The post on question also didn't call the author an idiot, just said that the paper was idiocy. That's not ad hominem at all.

Re:Rowhammer-like attack on SSDs can provide root privileges... by ericseppanen on Wednesday August 16, 2017 @05:52PM (#15031691)
Good modern SSDs do this. Cheap SSDs use only a non-cryptographic scrambler.
Re:Rowhammer-like attack on SSDs can provide root privileges... by street on Wednesday August 16, 2017 @03:43PM (#15030574)
Does flipping a bit in the ciphertext not flip the same bit in the plain text, for naive implementations?
Re:Rowhammer-like attack on SSDs can provide root privileges... by czinck on Wednesday August 16, 2017 @04:59PM (#15031332)
AES and similar algorithms are specifically designed to not do that, because otherwise details of the ciphertext leak details about the plaintext. https://en.wikipedia.org/wiki/Differential_cryptanalysis is about exploiting any unintentional leak of info like that.
Re:Rowhammer-like attack on SSDs can provide root privileges... by rocqua on Wednesday August 16, 2017 @05:56PM (#15031720)
AES in CTR mode does work like that. So do most stream ciphers.

Differential cryptanalysis is not about defending against bit-flips. Instead, it is about comparing two cipher texts to learn something about the relation between corresponding plain-text.

This is only possible on AES-CTR if you have to ciphertexts with the same key and nonce/IV. This is why a nonce is supposed to be used only once. Same goes for other xor based stream ciphers.

Re:Rowhammer-like attack on SSDs can provide root privileges... by dmitrygr on Wednesday August 16, 2017 @03:45PM (#15030590)
No because of SubBytes step
Re:Rowhammer-like attack on SSDs can provide root privileges... by the8472 on Wednesday August 16, 2017 @03:45PM (#15030595)
Not all cipher modes are immalleable.
Re:Rowhammer-like attack on SSDs can provide root privileges... by dmitrygr on Wednesday August 16, 2017 @03:46PM (#15030611)
AES without a known key doesn't allow modifications of a single output bit by only modifying plaintext and having no way to observe cyphertext.
Re:Rowhammer-like attack on SSDs can provide root privileges... by tedunangst on Wednesday August 16, 2017 @04:18PM (#15030983)
And which cipher modes are used by SSDs?
Re:Rowhammer-like attack on SSDs can provide root privileges... by dom0 on Thursday August 17, 2017 @03:45AM (#15034574)
Looking at this thread of comments a couple hours later, clearly, no one has an idea (so any security cleams seem unbased).
Re:Rowhammer-like attack on SSDs can provide root privileges... by dom0 on Wednesday August 16, 2017 @03:34PM (#15030468)
Not necessarily. Depending on the mode bitflips produce predictable results and a SSD probably does not authenticate blocks.
Re:Rowhammer-like attack on SSDs can provide root privileges... by dmitrygr on Wednesday August 16, 2017 @03:45PM (#15030596)
AES is not linear thanks to the SubBytes step. You don't know the key. Good luck :)
Re:Rowhammer-like attack on SSDs can provide root privileges... by dom0 on Wednesday August 16, 2017 @03:56PM (#15030723)
AES being linear or not is wholly irrelevant for this.

I recommend you read this article: https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation

Re:Rowhammer-like attack on SSDs can provide root privileges... by dmitrygr on Wednesday August 16, 2017 @04:00PM (#15030768)
Please explain how you'll mutate a single bit of output given only input and no knowledge of key
Re:Rowhammer-like attack on SSDs can provide root privileges... by bsder on Wednesday August 16, 2017 @08:28PM (#15032633)
Re:Rowhammer-like attack on SSDs can provide root privileges... by snakeanus on Wednesday August 16, 2017 @04:12PM (#15030908)
If you use a mode like CTR you just flip the corresponding ciphertext bit. As for CBC there are padding-oracle attacks.
Re:Rowhammer-like attack on SSDs can provide root privileges... by tedunangst on Wednesday August 16, 2017 @04:16PM (#15030962)
Do SSDs use CTR mode? How does one perform a padding oracle against an SSD? I feel like we're pretty far away from the relevant context, which is users corrupting data on an SSD.
Re:Rowhammer-like attack on SSDs can provide root privileges... by heheocoenev on Wednesday August 16, 2017 @05:36PM (#15031587)
XTS mode for block storage. Can't be CBC or CTR, where would you Store the IV or counter/nonce?
Re:Rowhammer-like attack on SSDs can provide root privileges... by Scaevolus on Wednesday August 16, 2017 @05:44PM (#15031635)
You could store it in the block metadata, which SSD flash translation layers already use for wear-leveling purposes.
Re:Rowhammer-like attack on SSDs can provide root privileges... by tedunangst on Wednesday August 16, 2017 @06:17PM (#15031843)
This sounds more like random speculation than informed commentary.
Re:Rowhammer-like attack on SSDs can provide root privileges... by rlanday on Wednesday August 16, 2017 @06:16PM (#15031836)
Does the SSD let you read the raw ciphertext to perform that attack? Or does it only expose the decrypted data?
Re:Rowhammer-like attack on SSDs can provide root privileges... by dmitrygr on Wednesday August 16, 2017 @08:07PM (#15032508)
There is no documented way to read cyphertext. I am SURE some manufacturer specific commands exist. But they will likely be undocumented, model-specific, and may be locked away behind a manufacturer key
Re:Rowhammer-like attack on SSDs can provide root privileges... by lightedman on Wednesday August 16, 2017 @10:54PM (#15033433)
"Please explain how you'll mutate a single bit of output given only input"

Same way Rowhammer works. Exploiting a physical vulnerability gives zero damns about encryption. Now whether you get VALID or USABLE data from the attack is an entirely different story.

Re:Rowhammer-like attack on SSDs can provide root privileges... by dijit on Wednesday August 16, 2017 @03:55PM (#15030708)
You're right. The AES key used on _all_ drives is 8bytes.

00000000

If it's anything else the user would have to enter the key. So in practice, it's not /really/ encrypted.

Re:Rowhammer-like attack on SSDs can provide root privileges... by Piskvorrr on Wednesday August 16, 2017 @04:15PM (#15030943)
Nope. The drive's firmware generates the key pseudorandomly when it receives the "securely wipe drive" command, this happens at least once before the drive is shipped from a factory. Thence, the key remains unchanged, unless another "securely wipe drive" command is received. This happens transparently to the user.
Re:Rowhammer-like attack on SSDs can provide root privileges... by leereeves on Wednesday August 16, 2017 @05:19PM (#15031462)
Every SSD works that way? Is that a standard?
Re:Rowhammer-like attack on SSDs can provide root privileges... by Piskvorrr on Wednesday August 16, 2017 @06:08PM (#15031787)
Bog-standard. As mentioned in sibling thread, you could find really old SSDs without this feature, but they're getting rare.
Re:Rowhammer-like attack on SSDs can provide root privileges... by ericseppanen on Wednesday August 16, 2017 @09:10PM (#15032846)
Drives that lack cryptographic scrambling are not rare. Search a few vendors' sites and you'll find some that don't support "self-encrypting" capabilities.
Re:Rowhammer-like attack on SSDs can provide root privileges... by wtallis on Wednesday August 16, 2017 @09:37PM (#15032995)
It's pretty common for drives to have hardware AES support even if they don't implement the full TCG Opal feature set for use as a "self encrypting drive". I think Phison is the only SSD controller vendor that doesn't advertise encryption capability on all of their mainstream SSD controllers.
Re:Rowhammer-like attack on SSDs can provide root privileges... by dijit on Thursday August 17, 2017 @07:10AM (#15035615)
I'm referencing work by the Drive Trust Alliance

https://github.com/Drive-Trust-Alliance/sedutil/wiki