This book constitutes the revised selected papers from the 11th International Conference on Risk and Security of Internet and Systems, CRISIS 2016, held in Roscoff, France, in September 2016.

This book constitutes the revised selected papers from the 12th International Conference on Risk and Security of Internet and Systems, CRISIS 2017, held in Dinard, France, in September 2017.The 12 full papers and 5 short papers presented in this volume were carefully reviewed and selected from 42 submissions.