4 ms·

Not that that's perfectly secure

by timdiggerm 11y ago

cwyers 11y ago
Yeah, it's only as secure as Tesla's ability to secure its private key.
- mikeash 11y ago
  And their ability to verify the signature on the car. Even if the private key is totally secure, you could either find a weakness in the signature verification, or find an exploit that lets you bypass it entirely.
  - UnoriginalGuy 11y ago
    That's an extremely rare vector for exploitation. I can think of one specific case where a vendor completely forgot to check the result of a signature check, but aside from that signature checking is well understood and rarely goes wrong. But to be honest people are taking their specification and dooms-day-ism to stupid extremes. Soon we'll be talking about "it is only as secure as the CPU, what if you find a CPU bug and bypass all security?!"
    - ZoFreX 11y ago
      > signature checking is well understood and rarely goes wrong I would argue otherwise, plenty of signature schemes give you enough rope to hang yourself. The Playstation 3 example springs to mind!
    - pigeons 11y ago
      Signature verification for android applications has been a tough one: http://www.saurik.com/id/19 http://www.saurik.com/id/19
- takeda 11y ago
  There's plenty room for bugs in mechanism like that. For example Motorola Droid (back in 2010) was locked and only accepted signed updates. There was a bug where you could bypass it by using authentic update and appending your payload at the end of that file.
  - thesteamboat 11y ago
    Interesting, can you point me to a news article or link? Shouldn't that have been rejected as an improperly signed file as (update+payload) should have a different signature than (update)? I'm want to know whether I'm misinterpreting something, misunderstanding something, or the signatures were misimplemented.
    - kuschku 11y ago
      Only the header was signed – that was the issue. It was made to save computational power on the device.
    - takeda 11y ago
      The original forum where it was posted doesn't exist anymore and there doesn't seem to be archived copy. Here's another page which is describing the steps: http://www.areacellphone.com/2009/12/motorola-droid-rooted-howto-root-droid/ http://www.areacellphone.com/2009/12/motorola-droid-rooted-h... Here is the commit with a bug fix: http://review.source.android.com/12807 http://review.source.android.com/12807 and actual diff: https://android-review.googlesource.com/#/c/12807/1/verifier.c https://android-review.googlesource.com/#/c/12807/1/verifier...

Not that that's perfectly secure

cwyers 11y ago

Yeah, it's only as secure as Tesla's ability to secure its private key.

mikeash 11y ago
And their ability to verify the signature on the car. Even if the private key is totally secure, you could either find a weakness in the signature verification, or find an exploit that lets you bypass it entirely.
- UnoriginalGuy 11y ago
  That's an extremely rare vector for exploitation. I can think of one specific case where a vendor completely forgot to check the result of a signature check, but aside from that signature checking is well understood and rarely goes wrong. But to be honest people are taking their specification and dooms-day-ism to stupid extremes. Soon we'll be talking about "it is only as secure as the CPU, what if you find a CPU bug and bypass all security?!"
  - ZoFreX 11y ago
    > signature checking is well understood and rarely goes wrong I would argue otherwise, plenty of signature schemes give you enough rope to hang yourself. The Playstation 3 example springs to mind!
  - pigeons 11y ago
    Signature verification for android applications has been a tough one: http://www.saurik.com/id/19 http://www.saurik.com/id/19
takeda 11y ago
There's plenty room for bugs in mechanism like that. For example Motorola Droid (back in 2010) was locked and only accepted signed updates. There was a bug where you could bypass it by using authentic update and appending your payload at the end of that file.
- thesteamboat 11y ago
  Interesting, can you point me to a news article or link? Shouldn't that have been rejected as an improperly signed file as (update+payload) should have a different signature than (update)? I'm want to know whether I'm misinterpreting something, misunderstanding something, or the signatures were misimplemented.
  - kuschku 11y ago
    Only the header was signed – that was the issue. It was made to save computational power on the device.
  - takeda 11y ago
    The original forum where it was posted doesn't exist anymore and there doesn't seem to be archived copy. Here's another page which is describing the steps: http://www.areacellphone.com/2009/12/motorola-droid-rooted-howto-root-droid/ http://www.areacellphone.com/2009/12/motorola-droid-rooted-h... Here is the commit with a bug fix: http://review.source.android.com/12807 http://review.source.android.com/12807 and actual diff: https://android-review.googlesource.com/#/c/12807/1/verifier.c https://android-review.googlesource.com/#/c/12807/1/verifier...