The NSA probably has the cryptographic keys (which they could easilly get with a FISA court order) for signing Microsoft Windows Updates, kernel drivers and so on, so I wouldn't be surprised if that is their main attack vector for Windows.

There are massive benefits for a State Surveillance and Electronic Espionage entity based in the country of the headquarters of the company that makes the OS and which has special Laws and special Surveillance Courts with secret court orders to let them get their hands directly on the data itself (if hosted on "the cloud") or the official digital keys for pushing whatever they want into computers running that OS.

Windows, iOS and MacOS should be treated by default as thoroughly compromised by the NSA, as should be any cloud hosting in the US or applications from companies based there.

This is not just an American thing: would you really trust a Russian OS or Chinese Data Hosting provider?

What I don’t get is, we all know the NSA is doing this. It’s no big secret. Why don’t they just report the 0-day to Microsoft, so they can fix it, so that North Korea doesn’t also exploit it. In exchange, Microsoft can give them some special access or special keys or some backdoor. Why even bother pretending anymore or putting on this charade. It’s the same thing over and over again.

During World War II, the telegraph interception guys would figure out which enemy units were where, even without having broken the codes, because each telegraph operators each had their own "fist," or distinct patterns in how they punched in the Morse code, and people listening to the signals day in and day out could learn to distinguish them even when dealing entirely in encrypted text.

In modern times, attribution of hacker groups include other indicators include what time zones certain people seem to be active in, what their targets are (and aren't), hints about installed language support or keyboard layouts or preferred punctuation or localized representations of numbers. For example, you can tell here on Lemmy when someone uses different types of quotation marks a decent indication of what country that person might be from, even in a totally English language thread.

For more on that, go listen to Darknet Diaries, episodes where they talk about major hacks are great