How are files replaced on a PC through Windows updates?

Question

Windows

How is it that after the arrival of updates on windows, folders appear with several users that are not related to PC users (System, administrators, username). Microsoft does not know what kind of crap it is, it says it's not ours, but the certificate of attorney costs MC.
99% sure it's a hacker attack. But how is this possible? Certificate forgery, OS deception?
Do I understand correctly that encryption of system folders is the way out (and folders in general)?

Answer 1

But how is this possible?

For example, "zero-day vulnerabilities".

Do I understand correctly that encryption of system folders is the way out (and folders in general)?

No, this will not help either from this, or from infection, or from ransomware.
Folder encryption is necessary so that no one gets access to your disk without a key (we do not take into account the soldering iron in one place). But since you give access to the disk to the operating system, then it (including programs - can do anything).