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The bumpy road towards iPhone 5c NAND mirroring
- campuscodi 10y agoI wonder how much the entire rig cost him? Not $1 million, that's for sure!
- dmitrygr 10y ago< $50 in parts (just a PIC24)
- ganoushoreilly 10y agoIt would have cost the agencies a lot more though (contracting fees), I highly doubt they'd have the technical capabilities to handle this. But it just goes to show that they didn't really reach out and were simply using it as a means to push their backdoor agenda. :(
- gizmo686 10y agoWhat worse is that they (or at least Comey) explicitly said that NAND mirroring does not work. When he was testifying before Congress, we was asked by several Congress people about NAND mirroring and (if I remember correctly) said that the technical experts had looked into it. This is either gross incompetence or outright perjury.
- dogma1138 10y agoWell for the FBI NAND mirroring might not be a solution. In the article the author mentions that this technique can effectively damage the flash memory because you can get effectively into a state where you are causing wear due to writes. In theory you can scale this up and copy the contents of memory into an FPGA which emulates NAND (both logically and physically) or just hold multiple copies on different chips but even the initial process is not without risk. While it's easy to say that the FBI lied or was incompetent because they had a motive to say set a precedent, but given the FBI's own rules for what is a forensically accepted method of extracting data NAND mirroring can easily be considered as something that "doesn't work".
- gizmo686 10y agoPerhaps the FBI had a valid reason for not doing NAND mirror [0]. However, I maintain that it is incompetent for the FBI director to testify before congress on the case and not be prepared with a basic answer to why the most obvious technical answer would not work. Similarly, with him saying in a press conference that it would not work. Of course, the FBI director does not need to know this level of detail about every case, but given how much he appears to have known, he should not have been speaking about the case beyond directing people to ask the person in charge of the case. [0] Although, I would argue, in cases where no alternative exists, if the FBI policies prevent NAND mirroring, they should be revisited. Even if it has the potential to be destructive, they would only be destroying otherwise unusable information.
- dogma1138 10y ago[0] Although, I would argue, in cases where no alternative exists, if the FBI policies prevent NAND mirroring, they should be revisited. Even if it has the potential to be destructive, they would only be destroying otherwise unusable information. Eh? no, destructive methods are a big no-no, this isn't a dichotomy. The information ins't unusable, they can try force apple to unlock the phone, or wait until some one else comes that can do it without using a destructive method. You can't destroy evidence because you can't do anything with it at the given time.
- deleted 10y ago[deleted]
- opello 10y ago> In theory you can scale this up and copy the contents of memory into an FPGA ... In practice it would have to be in external memory (DDR, flash, etc.) that the FPGA would use to back transactions because FPGAs don't have 32GB of memory capacity. Problems then become meeting bus timings that may very well be tuned for the PCB layout.
- xt00 10y agoYea they definitely just wanted the GovtOS from Apple. Basically would allow them to hack somebody's phone without them knowing. Whereas requiring them to disassemble the phone it would be more prone to error and take more time to do.
- dogma1138 10y agoThere are quite more parts to that, as well as the scope, logic analyzers and quite a few other components. It doesn't end up to 1M$ but it's also not 50$.
- sigmar 10y agoIt's stated in the end of the paper. Less than $100
- dogma1138 10y agoWith access to a research facility quality electronics lab, and they still haven't managed to create a functional backup on a new NAND chip. "Unfortunately, the 1:1 backup copy did not work in the iPhone 5c. Even the boot Apple logo did not appear on the power up. There were some references to hidden partitions used in iPhone NAND storage which makes cloning a challenging task."
- cmcfadden 10y ago... keep reading
- dogma1138 10y agoI kept reading, from what I understood they restored the copy on the original chip, not made a clone. They could use the backup process to restore a specific partition but then you have a problem of wear due to writes, they've said that a 6 pin passcode is unlikely to be able to be brute forced on a single NAND chip without inducing possible damage due to wear. Edit: You are correct, I've misread it.
- sigmar 10y agoLess than $100. It is stated on page 9
- cloudjacker 10y agoAre you suggesting that they minimized overhead and maximized profits, Mao is going to be livid!
- lisper 10y agoVindicated. https://news.ycombinator.com/item?id=11199093 https://news.ycombinator.com/item?id=11199093
- solipsism 10y agoI'm sure all the "experts" who were so vocal about how wrong you were will speak up now and admit they were wrong. Happens all the time around here. ;)
- CPLX 10y agoCan I come along and note that I was in that thread supporting that guy? Because that would be valuable for my self-esteem.
- deleted 10y ago[deleted]
- Evolved 10y agoThis is because many people don't care and/or switch to autopilot and double-down on their wrong point instead of being able to switch to a position where they can rationalize alternative answers and admit they are wrong. It is quite frustrating to deal with these people[0]. [0] https://youarenotsosmart.com/2011/06/10/the-backfire-effect/ https://youarenotsosmart.com/2011/06/10/the-backfire-effect/
- dogma1138 10y agoNo one with the slightest technical background thought the phone was uncrackable, maybe not directly by the FBI but by pretty much any 3rd party contractor that does even basic flash data recovery. The FBI was looking to set a precedent in order to be able to gain easy access to phones that could be also used by law enforcement, a local sheriff's department is less likely to be able to contract it out for every case and even if it would be a commodity it would be price prohibitive at scale. Overall probably even iPhones with a secure enclave are not "immune" to physical attacks, not as easy as doing simple nand-mirroring but if can decap the main CPU without destroying it you should be able to directly probe the secure enclave logic. Also while NAND mirroring does work, there is a good chance it wasn't used in that case, the current "theory" is that one of the patched USB DMA exploits were used to unlock the phone, NAND mirroring was too "risky" for the FBI to consider at the time, and it wasn't forensically secure IIRC one of the reasons for the very high price was the non-physical attack approach that the 3rd party provider they've selected had in their toolkit.
- CGamesPlay 10y agoProbably useful to mention this in the comments here: this works for the 5c, but not the 6 and beyond, due to the addition of the Secure Enclave.
- xt00 10y agoSo the secure enclave must have an embedded flash inside the processor that includes the pin code attempt counter -- meaning that writing to the external flash would not happen at all right?
- Sanddancer 10y agoFrom what Apple's released on how iPhone security works [1], it sounds like such keys are still written to external flash, just in a much more low-level way. So there may be a theoretical way to do this attack on a more recent iphone, but you'd have to do a lot more reverse engineering to figure out a few layers of undocumented proprietary protocols. [1] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf
- gizmo686 10y agoFrom skimming the paper, : "Each Secure Enclave is provisioned during fabrication with its own UID (Unique ID) that is not accessible to other parts of the system and is not known to Apple. When the device starts up, an ephemeral key is created, entangled with its UID, and used to encrypt the Secure Enclave’s portion of the device’s memory space. Additionally, data that is saved to the file system by the Secure Enclave is encrypted with a key entangled with the UID and an anti-replay counter. " This sounds like the secure enclave chip has a secret key, and all of its uses of external memory are encrypted using said key. This sounds like one would either need to break the crypto system itself, or compromise the secure enclave co-processor.
- firebones 10y agoHow would one provision a secure enclave at fabrication time? What does that even mean?
- Sniffnoy 10y agoA note -- if you're linking to arXiv, it's better to link to the abstract (https://arxiv.org/abs/1609.04327 https://arxiv.org/abs/1609.04327) rather than directly to the PDF. From the abstract, one can easily click through to the PDF; not so the reverse. And the abstract allows one to do things like see different versions of the paper, search for other things by the same authors, etc. Thank you!
- lisper 10y agoYou can also see when the paper was submitted.
- nickpsecurity 10y agoOh I find it so aggravating when I don't have a date. It seems like most academic papers I found on interesting security and programming stuff didn't have dates. I had to pull them off Citeseerx or the school's site. You'd think it would be a requirement in the style guides given importance of when something was published for relevance or context. I've never heard an explanation for why this isn't so. I do appreciate the authors that put one on there, though. Saves much Googling. :)
- tikhonj 10y agoConference papers include a copyright notice with the name (and year) of the conference. Papers that aren't published at conferences (preprints, technical reports... etc) don't have any standard format for this. Sometimes (especially for preprints) it's left out in expectation of adding the copyright notice in a future version, sometimes it's left out because the document is in a very preliminary stage and hasn't been officially published and sometimes it's left out because people just didn't think of it and there's no standard format that includes a date for things that aren't published to a specific venue.
- lisper 10y agoYou don't need a standard format. You just need to put "DRAFT - [today's date]" somewhere in the document.
- msoad 10y agohttps://news.ycombinator.com/item?id=11199275 https://news.ycombinator.com/item?id=11199275
- ChuckMcM 10y agoAwesome that someone actually took the time to do what many engineers suggested could be done.
- phyushin 10y agoInteresting read
- phyushin 10y agoInteresting read