Apple has just pushed an update to the data files used by XProtect, bringing its version number to 2136 dated 3 December 2020
Apple doesn’t release information about what these updates add or change, and now obfuscates the identities of malware detected by XProtect using internal code names. Changes found in the XProtect Yara definitions include the addition of a new detection signature for MACOS.1373c52, which hasn’t previously been detected by XProtect, and amendments to signatures for MACOS.8032420, MACOS.de444f2, MACOS.b70290c and MACOS.22d71e9.
You can check whether this update has been installed by opening System Information via About This Mac, and selecting the Installations item under Software.
A full listing of security data file versions is given by SilentKnight, LockRattler and SystHist for El Capitan, Sierra, High Sierra, Mojave, Catalina and Big Sur, available from their product page. If your Mac has not yet installed this update, you can force an update using SilentKnight, LockRattler, or at the command line.
I have updated the reference pages here which are accessed directly from LockRattler 4.2 and later using its Check blog button.
Thanks to Charles for alerting me to this update.