For Microsoft’s January patches, no all-clear (yet)
I’m not ready to give an all-clear to the security patches released Jan. 12, and I want to warn you about one specific update that is affecting HyperV servers and some consumer level workstations.
KB4535680, also known as Security update for Secure Boot DBX: January 12, 2021, makes improvements to Secure Boot DBX for a number of supported Windows versions. These include Windows Server 2012 x64-bit; Windows Server 2012 R2 x64-bit; Windows 8.1 x64-bit; Windows Server 2016 x64-bit; Windows Server 2019 x64-bit; Windows 10, version 1607 x64-bit; Windows 10; version 1803 x64-bit; Windows 10, version 1809 x64-bit; and Windows 10, version 1909 x64-bit. Key changes affect “Windows devices that [have] Unified Extensible Firmware Interface (UEFI) based firmware that can run with Secure Boot enabled.” The Secure Boot Forbidden Signature Database (DBX) prevents malicious UEFI modules from loading; this update adds additional modules to block malicious attackers who could successfully exploit the vulnerability, bypass secure boot, and load untrusted software.