That's a really naive view of how app development and deployment works, so I'll sum my response to it up with, "the admin who adds the header that breaks the Javascript in a major application is going to be fired within a single digit number of Unix timeslices of the change going live."
The problem with this stuff is that it requires virtually top-to-bottom surgery on real world apps. It is another naive view of applications that says that the dangerous inputs all come from form arguments.
Wait, what? Of course an admin wouldn't just turn it on out of the blue one day, and of course that would be really, really stupid, but admins on the edge are responsible for stuff like this all the time. Turning on compression, setting up firewall rules, configuring caches.
Companies serve old applications, companies serve applications built on different platforms, companies get caught without the resources to rewrite insecure applications that pay the bills. You really think this is something that an ops team wouldn't love to have in its toolbox, to use as needed and where appropriate?
The problem with this stuff is that it requires virtually top-to-bottom surgery on real world apps.
If you can't use it in your app or environment without a huge rewrite, then don't. If you can, then it's gravy.
It is another naive view of applications that says that the dangerous inputs all come from form arguments.
I never said or implied they did, and that's not the only threat this proposal addresses.
The difference between CSP and compression, firewall rules, and caching are that CSP alters the way the application works, and the others don't. I've seen drama just in getting modsecurity deployed, and modsecurity is much less intrusive than CSP.
The problem with this stuff is that it requires virtually top-to-bottom surgery on real world apps. It is another naive view of applications that says that the dangerous inputs all come from form arguments.