Title

The macOS system must be configured with dedicated user accounts to decrypt the hard disk upon startup. (Cat II impact)

Discussion

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.

Check Content

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/<FileVault_User> UserShell UserShell: /usr/bin/false If the FileVault users' shell is not set to "/usr/bin/false", this is a finding.

Fix Text

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 <username> /usr/bin/sudo /usr/bin/dscl . change /Users/<FileVault_User> UserShell </path/to/current/shell> /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 <username>

Additional Identifiers

Rule ID: SV-257160r905113_rule

Vulnerability ID: V-257160

Group Title: SRG-OS-000480-GPOS-00227

Expert Comments

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