Explore the security implications of ARM debugging features in this IEEE Symposium presentation. Delve into the ARM debugging architecture, including CoreSight components and debug registers, and examine the role of debug authentication signals. Investigate the shift from traditional physical access debugging to newer models that don't require it, raising concerns about potential vulnerabilities. Analyze the security of ARM debugging features across various product domains, including development boards, IoT devices, cloud servers, and mobile devices. Learn about the Nailgun attack, which exploits debugging features to obtain sensitive information and execute arbitrary payloads in high-privilege modes from low-privilege modes. Understand how this attack operates without relying on software bugs and affects a wide range of ARM-based platforms. Consider potential mitigations from different perspectives within the ARM ecosystem to address these security concerns.