The second Vienna Cyber Security Week (VCSW) held from 29 January to 2 February 2018 brought together representatives from public authorities, governments and organisations, including the International Telecommunications Union (ITU), the International Atomic Energy Authority (IAEA) and the Organization for Security and Co-operation in Europe (OSCE) for an international dialogue on the security of critical digital infrastructures. More than 300 high-level participants from 41 countries accepted the invitation and came to Vienna to engage in international dialogue on cyber security issues related to the energy sector. A total of 90 expert presentations and discussion groups as well as a technology exhibition and trainings provided the framework for examining how to protect our critical digital infrastructures from new crime & terrorism threat scenarios against critical energy infrastructure including security for smart cities.