If the [inter]national infrastructure goes down, with the firmware on every device on every internet-connected computer bricked at the same time due to a large-scale cyberattack (perhaps followed by a military attack a little while later), we're f-ed.
All this would take is:
- One zero-day each on Windows, MacOS, and Linux.
- Nation-state level resources to create a bricking firmware update for all commonly-used devices.
- Nation-state level resources to create a spreading attack for all major routers and network devices.
- Nation-state level resources to deploy this rapidly enough that response systems can't respond.
With 200 nation-states, it's perhaps just a matter of time....
(And yes, there's a lot more i's to dot and t's to cross, but I think they're all doable, with nation-state level resources)