5 ms·
Side-Channel attacks are nasty. Wonder why the FBI wasn't able to use this to hack the San Bernardino iPhone 5C, the NSA must be aware of this? From the article
by smartbit 11y ago
Side-Channel attacks are nasty. Wonder why the FBI wasn't able to use this to hack the San Bernardino iPhone 5C, the NSA must be aware of this? From the article
In the sequel, unless stated otherwise, the experiments were performed on Apple iPhone 3GS which exhibited a particularly clear signal.
Hope Apple fixes this in future models, even when opened.
- 05 11y agoSan Bernardino 5C could be cracked in two days using a NAND flash write blocker. You only need to program an FPGA to buffer writes to NAND chips in RAM instead of passing them through and to allow the reads, then you just try N PIN codes and reboot while resetting the blocker state cache. N is 4 if they haven't tried any PINs and 1 if there are delays after each because they've tried a couple PINs already. Phone boot time is ~1 minute, T(10000) = 10000 minutes / N (= a week if N==1)
- 13of40 11y agoDo you have a good citation for that or is it just a personal theory?
- mikeash 11y agoApple used to have a bug where they'd report PIN failure before writing that failure to nonvolatile storage. Somebody took advantage of this by building a box that cut power before the write could be performed, allowing a brute force attack: https://www.intego.com/mac-security-blog/iphone-pin-pass-code/ https://www.intego.com/mac-security-blog/iphone-pin-pass-cod... The proposal here is similar, just using a different technique to prevent the write. There isn't any nonvolatile storage besides the flash memory, so if you can reset that then the software has no way of knowing what happened before.
- dr_zoidberg 11y agoThanks for the link, it looks interesting.
- superuser2 11y agoNote that this was patched and is no longer feasible.
- 05 11y agoA personal theory. The iPhone Wiki has a description of iPhone storage structure - it seems newer phones (pre Secure Enclave) don't have separate NOR, NVRAM and NAND - they just use NAND for everything. [1] https://www.theiphonewiki.com/wiki/NOR https://www.theiphonewiki.com/wiki/NOR
- karlytypes 11y agoiOS 9, which apparently isn't vulnerable to this, was released 3 months prior to the San Bernardino attack. Furthermore, is a locked phone just sitting there performing time-dependent ECDSA signing operations all day long?
- tptacek 11y agoHow would that attack work? The key isn't resident; it's derived in part from the passcode. The target can't do any useful work with the key that could leak through side channels, because it doesn't have the key.