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Archive for the ‘FileVault 2’ Category

T2, FileVault and brute force attack protection

November 1, 2018 1 comment

Apple recently released an overview document for its new T2 chip, which includes how the new T2 chip-equipped Macs have new protections against brute force attacks. This protection only applies if FileVault is enabled and is similar in concept to how iOS devices set with passcodes are protected against brute force attacks.

On iOS, if an incorrect passcode is entered more than five times, a one minute delay is set.

Img 58462d7da9d03 477x600

After the sixth try, the delay is now five minutes and the delays get longer from there until the device has the 10th wrong passcode entered and the device wipes.

Screen Shot 2018 11 01 at 4 31 50 PM

On Apple iOS devices with a Secure Enclave, those delays are enforced by the Secure Enclave processor. Similarly, the T2 chip-equipped Macs also have a Secure Enclave processor which is managing access attempts and introducing delays.

For Macs with Secure Enclave, the enforcement looks like this:

  • 30 unlock attempts via using the password at the login window or target disk mode
  • 10 unlock attempts via using the password in Recovery Mode
  • 30 unlock attempts for each enabled FileVault recovery mechanism
    • iCloud recovery
    • FileVault personal recovery key
    • FileVault institutional recovery key

The maximum number of unlock attempts is 90, regardless of the mix of methods used. After 90 attempts, the Secure Enclave processor will no longer process any requests to do the following:

  • Unlock the volume
  • Decrypt the volume
  • Verify the password / recovery key

Delays are also imposed on macOS between attempts.

Screen Shot 2018 11 01 at 8 40 50 AM

So what happens after 90 attempts? Does the Mac lock forever and become a paperweight?

After checking with AppleCare Enterprise, the answer is that the Mac will not be a paperweight, but that the Mac’s boot drive will need to be erased before it can be used again. This approach helps make sure that the Mac is still usable, but also ensures that the encrypted data stored on the boot drive is no longer recoverable.

For more information about brute force protection for encrypted iOS and macOS devices, I recommend checking out Apple’s currently available white papers:

Detecting if a logged-in user on a FileVault-encrypted Mac has a Secure Token associated with their account

May 10, 2018 1 comment

A challenge many Mac admins have been dealing with is the introduction of the Secure Token attribute, which is now required to be added to a user account before that account can be enabled for FileVault on an encrypted Apple File System (APFS) volume.

In my own shop, we wanted to be able to identify if the primary user of a Mac had a Secure Token associated with their account. The reason we did this was:

  1. We could alert the affected help desk staff.
  2. We could work with our users to rebuild their Macs on an agreed-upon schedule where their data was preserved.
  3. We could hopefully avoid working with our users on an emergency basis where their data could be lost.

To help with this, we developed a detection script. For more details, please see below the jump.

Read more…

Session videos available from MacAD UK Conference 2018

March 29, 2018 1 comment

A number of session videos (including mine) have been posted from MacAD UK 2018. For those interested, the videos are available on YouTube via the link below:

https://www.youtube.com/playlist?list=PLe6gxSMzV0S_puM4DliqV0JD4pwlGgO1m

For convenience, I’ve linked my session here.

Cancelling an unwanted FileVault deferred enablement

March 12, 2018 Leave a comment

There are sometimes occasions when FileVault deferred encryption has been enabled for a particular Mac and then needs to be turned off. Since FileVault is not yet turned on at this point, there is no obvious way to turn off this deferred enablement.

However, it is possible to turn off a deferred enablement if needed. For more details, please see below the jump.

Read more…

Slides from the “Managing FileVault 2 on macOS High Sierra” Session at MacAD UK 2018 Conference

February 21, 2018 4 comments

For those who wanted a copy of my FileVault 2 management talk at MacAD UK 2018, here are links to the slides in PDF and Keynote format.

PDF – http://tinyurl.com/MacADUK2018pdf

Keynote – http://tinyurl.com/MacADUK2018key

Hat tip to the attendee who brought to my attention that fdesetup sync is not supported on encrypted APFS boot drives. I’ve now updated the slides to reflect that it works on macOS High Sierra for HFS+ drives only.

HFS+

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APFS

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FileVault management on macOS High Sierra session at Mac Admin & Developer Conference UK 2018

February 9, 2018 1 comment

I’ll be speaking at Mac Admin & Developer Conference UK 2018, which is taking place in London from February 20th – 21st, 2018. My session will be on Wednesday, February 21st and is covering FileVault management on macOS High Sierra, with discussion of how to manage encryption on both APFS and HFS Plus drives..

The full conference schedule is available from https://www.macad.uk/2018speakers/schedule/ and you can see the entire list of speakers at http://www.macad.uk/2018speakers/

Secure Token and FileVault on Apple File System

January 20, 2018 33 comments

As part of Apple File System’s FileVault encryption on mac OS High Sierra, Apple introduced Secure Token. This is a new and undocumented account attribute, which is now required to be added to a user account before that account can be enabled for FileVault on an encrypted Apple File System (APFS) volume. To help make sure that at least one account has a Secure Token attribute associated with it, a Secure Token attribute is automatically added to the first account to log into the OS loginwindow on a particular Mac.

Users and groups preference pane only user gets secure token automatically

Once an account has a Secure Token associated with it, it can then create other accounts which will in turn automatically be granted their own Secure Token.

For the consumer user, this usually takes the following form:

  1. Secure Token is automatically enabled for the user account created by Apple’s Setup Assistant.
  2. The Setup Assistant-created user account with Secure Token then creates other users via the Users & Groups preference pane in System Preferences. Those accounts get their own Secure Token automatically.

However, Active Directory mobile accounts and user accounts created using command line tools do not automatically get Secure Token attributes associated with these accounts. Without the Secure Token attribute, those accounts are not able to be enabled for FileVault.

Filevault preference pane account without secure token cannot manage filevault


Update 1-20-2018: @mikeymikey has pointed out an exception to the rule:


Instead, the sysadminctl utility must be used to grant Secure Token to these accounts as a post-account creation action. In that case, the sysadminctl utility must be run by a user account with the following pre-requisites:

  1. Administrative rights
  2. Secure Token

For more details, please see below the jump.

Read more…

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