The point of a sandbox is that the only things in it are the things you've put in it. A can only touch B through mechanisms interfaces it has been gifted. Compu

The point of a sandbox is that the only things in it are the things you've put in it. A can only touch B through mechanisms interfaces it has been gifted. Computer architecture is too broken to provide this guarantee to anything in the same address space, and operating systems are too broken to provide this guarantee through the majority of their interfaces. Proper, pervasive sandboxing in the architecture, ideally down to the function-level, would solve a huge fraction of security bugs, largely for free. Nobody would have had to invent Rust, because that 70% of memory safety bugs would have been almost entirely impossible to exploit from the start. I mean, it's pretty obvious the tension here is largely imaginary when you consider how much random code browsers run from untrusted sources, day after day, and most of those times they fail are because the architecture and OS and language haven't got sensible de-facto sandboxes (again, see that 70% number). For sure, you need to be careful what you give access to who, but the problem is insufficient sandboxing, and the solution is more sandboxing.