The shift in the IT industry to a computing platform characterized by data-driven insights, cloud-based computing, and engagement via mobile and social platforms heralds the dawn of the cognitive era in computing. Historically, during the transition from the mainframe to the PC and web eras, we have witnessed how security innovation has followed the industry platform shift, and the shift to a cognitive platform is no exception. Enterprises are looking for a new security model and paradigm that will enable them to confront and cope with the multitude of security challenges facing them. Based on our experiences with using big data techniques for security intelligence (starting in 2007), especially in customer environments, we have developed an operational model of security for securing enterprises, cloud environments, and the critical infrastructure. In this paper, we introduce Security 360°, a contextual, cognitive, and adaptive approach to protecting mission-critical assets, and illustrate a top-down approach to security that forms the basis of security research at IBM today.