AI systems like ChatGPT have advanced rapidly, yet their misuse has escalated in parallel. However, we still lack a systematic understanding of how AI systems are misused in the real world and why existing defenses repeatedly fail. This gap results in incomplete or misaligned safeguards, leaving individuals and society vulnerable. In this talk, I will share insights into the misuse of real-world AI systems, which involves understanding user-driven misuse in real-world AI systems, proactively detecting and mitigating AI system misuse, and identifying emerging security risks in the broader AI ecosystem.