4 ms·

Not impossible, but some smart people have been looking, at least for Apple's FileVault 2: http://www.schneier.com/blog/archives/2012/08/an_analysis_of.html ht

by Osmium 13y ago

Not impossible, but some smart people have been looking, at least for Apple's FileVault 2: http://www.schneier.com/blog/archives/2012/08/an_analysis_of.html http://www.schneier.com/blog/archives/2012/08/an_analysis_of... Paper here: http://eprint.iacr.org/2012/374.pdf http://eprint.iacr.org/2012/374.pdf Currently, there seem to be three vectors: 1) Weak passwords 2) If you opt-in to store a recovery key with Apple 3) If attacker has physical access to machine, and machine is powered on (direct memory access via Thunderbolt or Firewire) (Edit: seems like this is not the case, see below) But no backdoor has been found (yet!)

dmix 13y ago
> 3) If attacker has physical access to machine, and machine is powered on (direct memory access via Thunderbolt or Firewire) I'm curious if this could be addressed with software protections somehow? Something that triggers memory wipes and automatic shutdowns?
- anologwintermut 13y ago
  http://www.intel.com/content/www/us/en/architecture-and-technology/trusted-execution-technology/malware-reduction-general-technology.html http://www.intel.com/content/www/us/en/architecture-and-tech... Though that specifically obviously requires hardware.
  - dmix 13y ago
    It seems that only protects against "pre-launch software" and BIOS level stuff. The scenario in question is for a live system where the disk is mounted and decrypted, with the OS running.
- sil3ntmac 13y ago
  FileVault 2 is supposed to be secure against this* when the machine is powered on and locked or sleeping. * Source http://security.stackexchange.com/questions/18720/how-secure-is-filevault-2-while-the-computer-is-in-sleep-mode http://security.stackexchange.com/questions/18720/how-secure...
  - dmix 13y ago
    Interesting. Apparently LUKS/dmcrypt on Linux is also protected from DMA attacks (firewire/thunderbolt devices). > If you enable LUKS root, DMA attack mitigation is also enabled(boot.initrd.luks.mitigateDMAAttacks ). It consists of blacklisting firewire drivers. Edit: still at risk of the "Evil Maid Attack" http://www.aspecrypt.com/evil_maid_attack.html http://www.aspecrypt.com/evil_maid_attack.html
gecko 13y ago
3) If attacker has physical access to machine, and machine is powered on (direct memory access via Thunderbolt or Firewire) This may have changed, but turning on FileVault used to disable DMA in many situations (laptop had been suspended being a key one) until the user logged back in. Not that this isn't a vector, but it's actually a very narrow one; you basically need the person to already be logged in at the time you want to steal the keys.
- Osmium 13y ago
  Hmm, I didn't know that. It seems you may be right: http://www.frameloss.org/wp-content/uploads/2011/09/Lion-Memory-Acquisition.pdf http://www.frameloss.org/wp-content/uploads/2011/09/Lion-Mem... Though apparently there was a company offering a commercial solution for getting FileVault passwords using this method so... http://privacycast.com/filevault-vulnerability-how-to-protect-yourself-whole-disk-encryption-macos-lion/ http://privacycast.com/filevault-vulnerability-how-to-protec... There's also a really interesting pdf from Apple containing more details on FileVault 2: http://training.apple.com/pdf/WP_FileVault2.pdf http://training.apple.com/pdf/WP_FileVault2.pdf which suggests turning on firmware passwords to prevent DMA.
andrewgleave 13y ago
Take a look at Alex Ionescu's "Ninja's and Harry Potter" talk from NoSuchCon this year [1]. He specifically mentions he could access the FileVault key of a machine by having physical access, and discovered two secret keys (KPPW and KPST) one of which is enabled when the input buffer is "SpecialisRevelio" [2]. It's a very interesting deck to read through. [1] http://www.nosuchcon.org/talks/D1_02_Alex_Ninjas_and_Harry_Potter.pdf http://www.nosuchcon.org/talks/D1_02_Alex_Ninjas_and_Harry_P... [2] http://harrypotter.wikia.com/wiki/Specialis_Revelio http://harrypotter.wikia.com/wiki/Specialis_Revelio
- Osmium 13y ago
  That's really very interesting, and quite concerning. I saw that talk was only presented in May. Any new info since then?
blhack 13y ago
Why not just a backdoor in the OS? I mean...if we're seriously considering that apple would put a backdoor into FileVault, why not just put one in the OS proper? FileVault could be some hypothetical magic uncrackable encryption with a keyspace bigger than the known universe...and it would never matter if there was a backdoor in the OS.

by Osmium 13y ago

dmix 13y ago

> 3) If attacker has physical access to machine, and machine is powered on (direct memory access via Thunderbolt or Firewire) I'm curious if this could be addressed with software protections somehow? Something that triggers memory wipes and automatic shutdowns?

anologwintermut 13y ago
http://www.intel.com/content/www/us/en/architecture-and-technology/trusted-execution-technology/malware-reduction-general-technology.html http://www.intel.com/content/www/us/en/architecture-and-tech... Though that specifically obviously requires hardware.
- dmix 13y ago
  It seems that only protects against "pre-launch software" and BIOS level stuff. The scenario in question is for a live system where the disk is mounted and decrypted, with the OS running.
sil3ntmac 13y ago
FileVault 2 is supposed to be secure against this* when the machine is powered on and locked or sleeping. * Source http://security.stackexchange.com/questions/18720/how-secure-is-filevault-2-while-the-computer-is-in-sleep-mode http://security.stackexchange.com/questions/18720/how-secure...
- dmix 13y ago
  Interesting. Apparently LUKS/dmcrypt on Linux is also protected from DMA attacks (firewire/thunderbolt devices). > If you enable LUKS root, DMA attack mitigation is also enabled(boot.initrd.luks.mitigateDMAAttacks ). It consists of blacklisting firewire drivers. Edit: still at risk of the "Evil Maid Attack" http://www.aspecrypt.com/evil_maid_attack.html http://www.aspecrypt.com/evil_maid_attack.html

gecko 13y ago

3) If attacker has physical access to machine, and machine is powered on (direct memory access via Thunderbolt or Firewire) This may have changed, but turning on FileVault used to disable DMA in many situations (laptop had been suspended being a key one) until the user logged back in. Not that this isn't a vector, but it's actually a very narrow one; you basically need the person to already be logged in at the time you want to steal the keys.

Osmium 13y ago
Hmm, I didn't know that. It seems you may be right: http://www.frameloss.org/wp-content/uploads/2011/09/Lion-Memory-Acquisition.pdf http://www.frameloss.org/wp-content/uploads/2011/09/Lion-Mem... Though apparently there was a company offering a commercial solution for getting FileVault passwords using this method so... http://privacycast.com/filevault-vulnerability-how-to-protect-yourself-whole-disk-encryption-macos-lion/ http://privacycast.com/filevault-vulnerability-how-to-protec... There's also a really interesting pdf from Apple containing more details on FileVault 2: http://training.apple.com/pdf/WP_FileVault2.pdf http://training.apple.com/pdf/WP_FileVault2.pdf which suggests turning on firmware passwords to prevent DMA.

andrewgleave 13y ago

Take a look at Alex Ionescu's "Ninja's and Harry Potter" talk from NoSuchCon this year [1]. He specifically mentions he could access the FileVault key of a machine by having physical access, and discovered two secret keys (KPPW and KPST) one of which is enabled when the input buffer is "SpecialisRevelio" [2]. It's a very interesting deck to read through. [1] http://www.nosuchcon.org/talks/D1_02_Alex_Ninjas_and_Harry_Potter.pdf http://www.nosuchcon.org/talks/D1_02_Alex_Ninjas_and_Harry_P... [2] http://harrypotter.wikia.com/wiki/Specialis_Revelio http://harrypotter.wikia.com/wiki/Specialis_Revelio

Osmium 13y ago
That's really very interesting, and quite concerning. I saw that talk was only presented in May. Any new info since then?

blhack 13y ago

Why not just a backdoor in the OS? I mean...if we're seriously considering that apple would put a backdoor into FileVault, why not just put one in the OS proper? FileVault could be some hypothetical magic uncrackable encryption with a keyspace bigger than the known universe...and it would never matter if there was a backdoor in the OS.