[the_plus_one]

This is more on the user end, but there's ways for users to isolate programs in such a way that this malware wouldn't have access to e.g. browser files and cryptocurrency wallets, some more effective/practical than others. Virtual machines, containers, jails, chroots, etc.

I think one example of what you're talking about can be seen on Android. The developer has to explicitly declare permissions (like file access) in the manifiest, and the user has to explicitly approve it.