This document discusses controls for protecting critical information infrastructure from cyberattacks. It begins by examining vulnerabilities in critical information infrastructure that cyberthreats exploit to launch attacks, such as software vulnerabilities, personnel vulnerabilities, and network protocol vulnerabilities. It then analyzes various cyberthreats like malware, distributed denial of service attacks, cyberwarfare, and social engineering that target these vulnerabilities. The document proposes implementing a system of preventive, detective, and corrective security controls based on general systems theory to address the vulnerabilities. Finally, it presents a model for securing critical information infrastructure that is currently insecure.