Windows 10 systems must use a BitLocker PIN with a minimum length of six digits for pre-boot authentication.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-220704	WN10-00-000032	SV-220704r859297_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. Increasing the PIN length requires a greater number of guesses for an attacker.

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. Increasing the PIN length requires a greater number of guesses for an attacker.

STIG	Date
Microsoft Windows 10 Security Technical Implementation Guide	2023-04-26

Details

Check Text ( C-22419r819654_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: MinimumPIN Type: REG_DWORD Value: 0x00000006 (6) or greater

Check Text ( C-22419r819654_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: MinimumPIN
Type: REG_DWORD
Value: 0x00000006 (6) or greater

Fix Text (F-22408r554598_fix)
Configure the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> BitLocker Drive Encryption >> Operating System Drives "Configure minimum PIN length for startup" to "Enabled" with "Minimum characters:" set to "6" or greater.