I. Introduction
The number of adversaries, and their skill level, attacking a network defender are key informational components to defensive planning. However, estimating the extent of adversarial capability has historically been difficult, especially in the cyber domain. This paper describes a model to better estimate and reason about global adversarial capability and the landscape of computer network attacks (CNA). The model identifies and clarifies trends in the progression of adversary capabilities and provides a clearer view of the global threat landscape.