The document discusses injecting threat modeling into the software development lifecycle (SDLC). It provides examples of security issues that could have been prevented with threat modeling, such as the Equifax data breach. Threat modeling is a structured approach to identify, quantify, and address security risks. It should be used during requirements, design, and development phases of both new and existing functionality. The process involves data flow diagrams, identifying threats and proposed responses, prioritizing mitigations, and using techniques like STRIDE. Threat modeling sessions should gather documentation and cross-functional teams to holistically understand risks. Identified risks are then evaluated and prioritized to determine how to handle each risk.