Information
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.
Solution
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.