Regarding file permissions: This kind of archeaology (or forensics) is very important. Why? Because it exposes the trial-and-error over a multi-decade evolution

Regarding file permissions: This kind of archeaology (or forensics) is very important. Why? Because it exposes the trial-and-error over a multi-decade evolution. Sometimes trial-and-error is used as a pejorative (brute force hacking), but over the course of decades as technology advances, it is inevitable. The author is clear to point out that much of the issue here was due to scalability, but i think there is something else at work: unknown unknowns. It is impossible to be a 100% defensive software architecture team, and "room to grow" is usually jettisoned because it can lead to sloppy code, or worse, attack vectors. It's such a hard problem and analyses like these papers are first step in what I believe will become a full-blown historic discipline of software meta-thought. I say "become" because you can't really do this kind of analysis with 5, 10 or 20 years of history: you need multiple decades, and that is just now upon us. I think there are applications for this kind of study. It can very clearly feed back into current practices, and possibly even more formalized language syntax that can be defensive and extensible. I would also love to see if this kind of analysis bears out which aspects of various languages (and architectural OS decisions) proved to be the most robust. Like with hemaglobin: it is one of the largest and oldest genes, it is hard to break via mutatation, and is shared by every animal with oxygenated blood cells. Something was done right with that design!