News for hackers. Stuff that matters.

A comment on Nasty macOS flaw is bricking MacBooks: Don't install this update. Parent comment

Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by tbagman on Sunday April 12, 2020 @10:34AM (#22848507)
Confirmed; this is what happened to my 16" after this install. I needed to do a DFU restore (using Apple Configurator 2 -- you can download it to your hopefully spare MacBook from the app store) to get my mac back up and running. Unfortunately, for some reason, after the DFU restore, my 16" came back up to do a full reinstall, and I had to restore my files from backup.

Took a day, but all's well now.

[ Parent | on HN ]
Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by bnt on Sunday April 12, 2020 @10:45AM (#22848568)
I hope Apple doesn’t expect that everyone has a “Spare Macbook” laying around. I’ve been experiencing random system crashes when anything connects via TB3, and 3 random Kernel panics since the update.
[ Parent | on HN ]
Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by floatingatoll on Sunday April 12, 2020 @11:05AM (#22848687)
The SSD in a T2 Mac is encrypted in the same way that an iPhone is, so if the DFU crashes hard enough you’ll have to regenerate new keys and that’s equivalent to drive zero.

Glad it helped.

[ Parent | on HN ]
Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by jplayer01 on Sunday April 12, 2020 @12:07PM (#22849118)
Is it possible to export a recovery key? Because this kind of failure simply due to a bad update shouldn't be acceptable.
[ Parent | on HN ]
Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by floatingatoll on Sunday April 12, 2020 @03:07PM (#22850366)
No, it’s not possible to use a FileVault recovery key at this stage of repair.

It’s not failure, it’s secure by design to prevent attackers/governments from stealing your files without consent.

Under DFU brick and reset circumstances, the private key is gone, because otherwise an attacker could just upload a hacked firmware via DFU and access all your files.

I assume the installer uses a different process that performs a DFU upgrade-in-place that safely manages the handoff using signed code and such, but that’s not the process we get as a last restore described above.

If you don’t have off-device backups, you’re accepting the risk of losing all your data at any time due to any number of possible failures (software and hardware). Not much use getting upset about this specific case.

[ Parent | on HN ]
Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by jplayer01 on Monday April 13, 2020 @05:15PM (#22860070)
Not sure what DFU means as I'm not familiar with Mac. With any other encryption, it doesn't matter what the state of my system is. As long as I have the key, I can always decrypt it. And it's not a vulnerability. Without the key, the data is effectively inaccessible for everybody else (except maybe somebody with a quantum computer).
[ Parent | on HN ]
Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by pvg on Sunday April 12, 2020 @01:43PM (#22849789)
You get a recovery key when the original key is generated.
[ Parent | on HN ]
Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by floatingatoll on Sunday April 12, 2020 @03:10PM (#22850381)
Yes: You can export a FileVault recovery key when enabling FileVault, whether on a T2 Mac or not.

No: There’s no opportunity to use FileVault recovery keys when you’re doing a DFU on a T2 Mac. If you have to DFU, your data is lost.

(edited to clarify per reply)

[ Parent | on HN ]
Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by pvg on Sunday April 12, 2020 @03:24PM (#22850454)
That wasn't the question I was answering or was asked, I think.
[ Parent | on HN ]
Re:Nasty macOS flaw is bricking MacBooks: Don't install this... by ThePowerOfFuet on Sunday April 12, 2020 @12:25PM (#22849227)
No.
[ Parent | on HN ]