The goal of this paper is to help decision-makers and entities who can protect systems from ransomware at scale, such as the security industry, governments, and policymakers, to form defensive strategies on how best to make an impact on the ransomware ecosystem. While this paper does not focus on hands-on technical defenses that an enterprise would look to for deployment, it does aim to provide decision-makers with methods for understanding the level of risk that an organization faces from this threat.