Shostack + Friends Blog Archive


Putting the fun back in threat modeling

I have an article in the latest MSDN magazine, “Reinvigorate your threat modeling process:”

My colleague Ellen likes to say that everyone threat models all the time. We all threat model airport security. We all threat model our homes. We think about threats against our assets: our families, our jewelry, and our sentimental and irreplaceable photographs (well, those of us old enough to have photos that never existed in digital form do). We model threats based on architecture: there’s a wall here, a picture window there, and an easily climbed tree that we can use when we forget our keys. And we model threats based on attackers. We worry about burglars and kids falling into pools. We also worry about the weather, be it earthquakes, snow, or tornadoes.

If I wanted to sound like a management consultant, I’d say you employ a mature, multi-dimensional assessment process, with a heavy reliance on heuristics and low reproducibility across instances. At the same time, it’s likely you won’t have thought of everything or implemented defenses against every possible attack. It’s very unlikely you have a home defense management plan or have ever run a penetration test against your home.

There’s a lot in there talking about how and why some threat modeling methods became “heavy” and what to do about it. Underlying that is the start of a way of thinking about threat modeling as a family of related activities, and some ways of breaking that down. In particular, there’s a breakdown into asset-centric, architecture-centric, and attacker-centric threat modeling, which I think is a useful step forward.

What works for you in threat modeling? What hasn’t worked that you needed to replace?

2 comments on "Putting the fun back in threat modeling"

  • Alex says:

    The biggest problem I have in threat (or risk) modeling is the removal of bias in assigning probabilities. The most common problem I’ve encountered is the inability to provide rigor around the methods used to determine the probabilities.

  • I think the problem is actually how easily duped people are in certain cultures. [link no longer works]

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