Fortunately, this was not the case. Microsoft didn't reveal a whole lot of details but informed the press that the KB3877432 update was rolled out by accident and that the company is in the process of removing it.
Microsoft said a highly suspicious Windows update that was delivered to customers around the world was the result of a test that wasn't correctly implemented.ARS Technica
"We incorrectly published a test update and are in the process of removing it," a Microsoft spokesperson wrote in an e-mail to Ars. The message included no other information.
The explanation came more than 12 hours after people around the world began receiving the software bulletin through the official Windows Update, raising widespread speculation that Microsoft's automatic patching mechanism was broken or, worse, had been compromised to attack end users. Fortunately, now that Microsoft has finally weighed in, that worst-case scenario can be ruled out.