This document discusses the importance and challenges of defensive cybersecurity research. It notes that while offensive research may be easier due to exploitable technology vulnerabilities, defensive research is important for protecting systems and data from attackers. Defensive research involves efforts like finding and mitigating vulnerabilities, developing detection and response capabilities, understanding evolving attack techniques, and improving security standards and implementations. The document outlines many open challenges in areas like phishing, malware, memory corruption, and forensics. It argues that to be successful, defensive ideas must be practical, scalable, cost-effective, and widely adopted. The rewards of defensive research are more intangible compared to offensive research, but are still very important for enhancing security.