Windows 10 systems must use a BitLocker PIN for pre-boot authentication.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-220703	WN10-00-000031	SV-220703r819653_rule		Medium

Description
If data at rest is unencrypted, it is vulnerable to disclosure. Even if the operating system enforces permissions on data access, an adversary can remove non-volatile memory and read it directly, thereby circumventing operating system controls. Encrypting the data ensures that confidentiality is protected even when the operating system is not running. Pre-boot authentication prevents unauthorized users from accessing encrypted drives.

Description

If data at rest is unencrypted, it is vulnerable to disclosure. Even if the operating system enforces permissions on data access, an adversary can remove non-volatile memory and read it directly, thereby circumventing operating system controls. Encrypting the data ensures that confidentiality is protected even when the operating system is not running. Pre-boot authentication prevents unauthorized users from accessing encrypted drives.

STIG	Date
Microsoft Windows 10 Security Technical Implementation Guide	2022-04-08

Details

Check Text ( C-22418r819652_chk )
If the following registry value does not exist or is not configured as specified, this is a finding. For virtual desktop implementations (VDIs) in which the virtual desktop instance is deleted or refreshed upon logoff, this is NA. For Azure Virtual Desktop (AVD) implementations with no data at rest, this is NA. Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SOFTWARE\Policies\Microsoft\FVE\ Value Name: UseAdvancedStartup Type: REG_DWORD Value: 0x00000001 (1) If one of the following registry values does not exist or is not configured as specified, this is a finding. Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SOFTWARE\Policies\Microsoft\FVE\ Value Name: UseTPMPIN Type: REG_DWORD Value: 0x00000001 (1) Value Name: UseTPMKeyPIN Type: REG_DWORD Value: 0x00000001 (1) When BitLocker network unlock is used: Value Name: UseTPMPIN Type: REG_DWORD Value: 0x00000002 (2) Value Name: UseTPMKeyPIN Type: REG_DWORD Value: 0x00000002 (2) BitLocker network unlock may be used in conjunction with a BitLocker PIN. Refer to the article at the link below for information about network unlock. https://docs.microsoft.com/en-us/windows/security/information-protection/bitlocker/bitlocker-how-to-enable-network-unlock

Check Text ( C-22418r819652_chk )

If the following registry value does not exist or is not configured as specified, this is a finding.

For virtual desktop implementations (VDIs) in which the virtual desktop instance is deleted or refreshed upon logoff, this is NA.

For Azure Virtual Desktop (AVD) implementations with no data at rest, this is NA.

Registry Hive: HKEY_LOCAL_MACHINE
Registry Path: \SOFTWARE\Policies\Microsoft\FVE\

Value Name: UseAdvancedStartup
Type: REG_DWORD
Value: 0x00000001 (1)

If one of the following registry values does not exist or is not configured as specified, this is a finding.

Registry Hive: HKEY_LOCAL_MACHINE
Registry Path: \SOFTWARE\Policies\Microsoft\FVE\

Value Name: UseTPMPIN
Type: REG_DWORD
Value: 0x00000001 (1)

Value Name: UseTPMKeyPIN
Type: REG_DWORD
Value: 0x00000001 (1)

When BitLocker network unlock is used:

Value Name: UseTPMPIN
Type: REG_DWORD
Value: 0x00000002 (2)

Value Name: UseTPMKeyPIN
Type: REG_DWORD
Value: 0x00000002 (2)

BitLocker network unlock may be used in conjunction with a BitLocker PIN. Refer to the article at the link below for information about network unlock.

https://docs.microsoft.com/en-us/windows/security/information-protection/bitlocker/bitlocker-how-to-enable-network-unlock

Fix Text (F-22407r554595_fix)
Configure the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> BitLocker Drive Encryption >> Operating System Drives "Require additional authentication at startup" to "Enabled" with "Configure TPM Startup PIN:" set to "Require startup PIN with TPM" or with "Configure TPM startup key and PIN:" set to "Require startup key and PIN with TPM".