I then started reading: https://www.vice.com/en/article/qvakb3/inside-nso-group-spyware-demo https://www.vice.com/en/article/pkyzxz/spain-nso-group-pegasus-catalonia
If NSO Group and many other companies and intelligence agencies are actively developing zero-days, how can one protect against it?
Is security through obscurity (e.g. using the PinePhone or an unknown platform) the only option?
I'm only really asking about individual solutions to protect data, rather than systemic ones, like the recommendation by the U.N. Special Rapporteur on freedom of expression for a global moratorium on the sale and transfer of surveillance technology. Such systemic solutions seem unlikely as of yet.
I think MOST orgs don't have to worry about NSO or state-level actor attacks. Most orgs are far more susceptible to ransomware and phishing, and should focus first on those.
The best approach to mitigating Zero-days is _detection_, to be honest. Would your shop be able to detect files flowing out? Odd time access? Weird probes from a computer inside the network? Security through obscurity is never a good solution. That means bespoke stuff that might be hard to work with, but doesn't necessarily improve your security posture.
You want to develop a deep defense with good detection and monitoring with review. That will help you not just with Zero days, but all security aspects.
[1] - https://en.wikipedia.org/wiki/Linux_Security_Modules
[2] - https://www.pine64.org/pinephone/
[3] - https://man7.org/linux/man-pages/man7/capabilities.7.html
Otherwise, assume basically all software and hardware is vulnerable for a price if it's anywhere near anything that can connect to a wireless network or bluetooth device.