Threat Modeling the PASTA Way
There’s a really interesting podcast with Robert Hurlbut Chris Romeo and Tony UcedaVelez on the PASTA approach to threat modeling. The whole podcast is interesting, especially hearing Chris and Tony discuss how an organization went from STRIDE to CAPEC and back again.
There’s a section where they discuss the idea of “think like an attacker,” and Chris brings up some of what I’ve written (“‘Think Like an Attacker’ is an opt-in mistake.”) I think that both Chris and Tony make excellent points, and I want to add some nuance around the frame. I don’t think the opposite of “think like an attacker” is “use a checklist,” I think it’s “reason by analogy to find threats” or “use a structured approach to finding threats.” Reasoning by analogy is, admittedly, hard for a variety of reasons, which I’ll leave aside for now. But reasoning by analogy requires that you have a group of abstracted threats, and that you consider ‘how does this threat apply to my system?’ You can use a structured approach such as STRIDE or CAPEC or an attack tree, or even an unstructured, unbounded set of threats (we call this brainstorming.) That differs from good checklists in that the items in a good checklist have clear yes or no answers. For more on my perspective on checklists, take a look at my review of Gawande’s Checklist Manifesto.