Details

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.

Solution

Create an authorized user account that will be used to unlock the disk on startup.

Disable the login ability of the newly created user account:

# sudo dscl . append /Users/ AuthenticationAuthority DisabledUser

Disable the FileVault Auto-login feature:

# sudo defaults write /Library/Preferences/com.apple.loginwindow DisableFDEAutologin -bool YES

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

# sudo fdesetup remove -user

Supportive Information

The following resource is also helpful.

• https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Apple_OS_X_10-15_V1R7_STIG.zip

This security hardening control applies to the following category of controls within NIST 800-53: Configuration Management.This control applies to the following type of system Unix.

References

• 800-53|CM-6b.
• CAT|II
• CCI|CCI-000366
• CSCv6|13.2
• Rule-ID|SV-225222r610901_rule
• STIG-ID|AOSX-15-000032
• STIG-Legacy|SV-111655
• STIG-Legacy|V-102693
• Vuln-ID|V-225222

Source

• Tenable.com/audits