Title

Windows Server 2019 systems must have Unified Extensible Firmware Interface (UEFI) firmware and be configured to run in UEFI mode, not Legacy BIOS. (Cat III impact)

Discussion

UEFI provides additional security features in comparison to legacy BIOS firmware, including Secure Boot. UEFI is required to support additional security features in Windows, including Virtualization Based Security and Credential Guard. Systems with UEFI that are operating in "Legacy BIOS" mode will not support these security features.

Check Content

Some older systems may not have UEFI firmware. This is currently a CAT III; it will be raised in severity at a future date when broad support of Windows hardware and firmware requirements are expected to be met. Devices that have UEFI firmware must run in "UEFI" mode. Verify the system firmware is configured to run in "UEFI" mode, not "Legacy BIOS". Run "System Information". Under "System Summary", if "BIOS Mode" does not display "UEFI", this is a finding.

Fix Text

Configure UEFI firmware to run in "UEFI" mode, not "Legacy BIOS" mode.

Additional Identifiers

Rule ID: SV-205856r991589_rule

Vulnerability ID: V-205856

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

Expert Comments

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Controls tied to check. These are derived from the CCIs shown above.