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The macOS system must be configured with dedicated user accounts to decrypt the hard disk upon startup.


Overview

Finding ID Version Rule ID IA Controls Severity
V-257160 APPL-13-000032 SV-257160r905113_rule Medium
Description
When "FileVault" and Multifactor Authentication are configured on the operating system, a dedicated user must be configured to ensure that the implemented Multifactor Authentication rules are enforced. If a dedicated user is not configured to decrypt the hard disk upon startup, the system will allow a user to bypass Multifactor Authentication rules during initial startup and first login.
STIG Date
Apple macOS 13 (Ventura) Security Technical Implementation Guide 2023-08-28

Details

Check Text ( C-60845r905111_chk )
Verify the macOS system is configured with dedicated user accounts to decrypt the hard disk upon startup with the following command:

/usr/bin/sudo /usr/bin/fdesetup list

fvuser,85F41F44-22B3-6CB7-85A1-BCC2EA2B887A

If any unauthorized users are listed, this is a finding.

Verify that the shell for authorized FileVault users is set to "/usr/bin/false" to prevent console logons:

/usr/bin/sudo /usr/bin/dscl . read /Users/ UserShell

UserShell: /usr/bin/false

If the FileVault users' shell is not set to "/usr/bin/false", this is a finding.
Fix Text (F-60786r905112_fix)
Configure the macOS system with a dedicated user account to decrypt the hard disk at startup and disable the logon ability of the newly created user account with the following commands:

/usr/bin/sudo /usr/bin/fdesetup add -user

/usr/bin/sudo /usr/bin/dscl . change /Users/ UserShell /usr/bin/false

Remove all FileVault logon access from each user account defined on the system that is not a designated FileVault user:

/usr/bin/sudo /usr/bin/fdesetup remove -user