Very similar to the CCleaner hack - many infected, but few targeted:
https://www.kaspersky.com/blog/shadow-hammer-teaser/26149/
(My thanks to exile360 at Malwarebytes forum for flagging this).
It did happen a couple of months ago and Asus supplied a new updater
I should have noted the date on that Kaspersky article, it is a couple of months old.
Checking here I did make a post about it at the time. (Must be alzheimer's kicking in).
Allot of the "updaters" are made by another company for many PC manufacturers, unfortunately allot of them get hopelessly outdated and even more somewhat useless in short order if they don't give a system necessary updates.