Overnight, Apple has pushed two updates, to the data files used by XProtect, bringing its version number to 2145 dated 29 April 2021, and to its malware removal tool MRT, bringing it to version 1.78, also dated 29 April 2021.
Apple doesn’t release information about what these updates add or change, and 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 signature for MACOS.2b50ea5, and changed signatures for MACOS.1db9cfa (XCSSET variants, which Apple had named DUBROBBER.D) and MACOS.6eaea4b (XCSSET variants, which Apple had named DUBROBBER.E). Apple has also removed comments identifying DUBROBBER malware.
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.
I maintain lists of the current versions of security data files for Big Sur on this page, Catalina on this page, Mojave on this page, High Sierra on this page, Sierra on this page, and El Capitan on this page.
I am grateful to Phil Stokes at Sentinel Labs for decoding of the obfuscated malware names here.