Abstract: Over the past ten years, the adoption of cloud services has grown rapidly, leading to the introduction of automated deployment tools to address the scale and complexity of the infrastructure companies and users deploy. Without the aid of automation, ensuring the security of an ever-increasing number of deployments becomes more and more challenging. To the best of our knowledge, no formal automated technique currently exists to verify cloud deployments during the design phase. In this case study, we show that Description Logic modeling and inference capabilities can be used to improve the safety of cloud configurations. We focus on the Amazon Web Services (AWS) proprietary declarative language, CloudFormation, and develop a tool to encode template files into logic. We query the resulting models with properties related to security posture and report on our findings. By extending the models with dataflow-specific knowledge, we use more comprehensive semantic reasoning to further support security reviews. When applying the developed toolchain to publicly available deployment files, we find numerous violations of widely-recognized security best practices, which suggests that streamlining the methodologies developed for this case study would be beneficial.