Yup, that's the pop-up that's got people baffled.
Thank you for the clearest, to-the-point statement yet on this entire thread from a Word MVP. "Trial basis" and "third party" are not my words - they were spoken by MS Technical Support. Support also told me the manufacturer of the computer installed the
software, and then explained the "trial basis" part followed by the "third party" part. I didn't ask who the "third party" was.
The only reason I called support was because I did not read a clear answer, in plain, easy to understand English from MS on this thread such as "Yes, that pop-up is from Microsoft. You should click OK and download it."
The only reason I went to this thread was because like some other people I've got some security concerns. I no sooner finish reading about the latest ransomware trojan, Cryptolocker 2.0, and this bogus looking pop up appears on my screen.
As of this reply, there's 93 replies to the question. I believe there should only be about 2 or 3 posts with a clear statement from Microsoft stating "Yes, this is an official Microsoft update."
If I hadn't found a phone number I was going to write a letter and I was going to mail it to Redmond.
I still may.
Hope this helps.