Justin's research interests generally fall broadly in the area of systems security. He focuses on understanding high-impact, large-scale problems by building and measuring deployed systems. Prof. Cappos did his dissertation work describing flaws in prior Linux package managers and building / deploying a new security model. His work on software update system security was deployed by the major Linux package managers (e.g. apt, yum, and YaST) and thus protects most Linux servers. Due to the practical impact of his research, Prof Cappos was named in 2013 as one of Popular Science's Brilliant 10 scientists under 40.