Brainstorming

One of the most simple ways to identify threats is to host a brainstorming session. Brainstorming can be broken down into (1) a period of idea generation, and (2) a period of filtering where the best ideas are selected. Before brainstorming, it is often helpful to define the scope of attacks under consideration.

On its own, brainstorming is not a sufficient form of threat modelling. This is because it is (deliberately) unstructured, and does not provide a high degree of confidence that all threats have been identified - i.e., did your brainstorming session end because you found all threats, or because you became tired / the meeting ended?

Brainstorming Variants

Beyond the atypical ‘free-form’ brainstorming, there are several specific methods that may be used.

Scenario Analysis

In this variant, brainstorming begins with scenarios - e.g., Chandler’s Law (“When in doubt, have a man come through the door with a gun.”)

Pre-Mortem

Consider a group of those involved in a decision gathered in a room. Ask the group to pretend it is shortly after a project deadline, and that things have gone awry. Ask the group to hypothesise why they believe things have gone awry.

With this method, the natural optimism that accompanies a project is replaced with an explicit assumption that it has failed, giving you and other participants a chance to express doubts.

Movie Plotting

In this variant, attacks are deliberately intended to be as outrageous and provocative as possible. This is done to encourage the free flow of ideas.