These proceedings represent the work of researchers participating in the 12th International Conference on Cyber Warfare and Security (ICCWS 2017) which is being hosted this year by Wright State University with support from the Air Force Institute of Technology in Dayton, Ohio, USA on 2-3 March 2017. ICCWS is a recognised event on the International research conferences calendar and provides a valuable platform for individuals to present their research findings, display their work in progress and discuss conceptual and empirical advances in the area of Cyberwar and Cyber Security. It provides an important opportunity for researchers and managers to come together with peers to share their experiences of using the varied and expanding range of Cyberwar and Cyber Security research available to them. The conference this year will be opened with a keynote presentation by The Adjutant General of Indiana, Major General Courtney P. Carr who will address the topic Total Force Cyber: Working in an Ambiguous Environment. The second day of the conference will be opened by Dr. Matt Bishop from the University of California at Davis. Matt will be talking about Resilience as a Security Property. With an initial submission of 154 abstracts, after the double blind, peer-review process there are 32 academic Research papers, 7 PhD Research, 5 Masters Research 1 Non-Academic and 6 Work in Progress papers published in these Conference Proceedings. These papers represent truly global research in the field, with contributions from Canada, Ecuador, Estonia, Finland, France, Germany, Malaysia, Netherlands, Nigeria, Peru, Portugal, Russia, Saudi Arabia, South Africa, USA, and UK.