I have previously given talks about security principles and approaches like Least Privilege, TCB Minimization, and Self Sandboxing. The most frequent feedback has been "I don't know how to apply this in practice". So, in this talk, I will show how I applied those principles in a real-world software project: a CRUD web app. My blog. I introduced dangerous attack surface on purpose so I could some day give a talk about how to apply these techniques to reduce risk. This is that talk. I will also introduce the concept of append-only data storage.