This book constitutes the refereed proceedings of the 18th International Conference on Critical Information Infrastructures Security, CRITIS 2023, held in Helsinki region, Finland, during September 13–15 2023.The 13 full papers and 3 short papers and one Paper in Progress were carefully selected from 25 submissions.

.- Mapping and Analysis of Common Vulnerabilities in Popular Web Servers. .- Assessing the Effect of the Lack of Essential Workforce on the Economic Sectors during a Pan-demic. .- Ethics and the threat to infrastructure. .- Short and Long Term Vessel Movement Prediction for Maritime Traffic. .- Managing Uncertainty using CISIApro 2.0 Model. .- Adaptable Smart Distribution Grid Topology Generation for Enhanced Resilience. .- Business Continuity Management – Building Block of Dynamic Resilience. .- Evasion Attack against Multivariate Singular Spectrum Analysis based IDS. .- Vulnerability analysis of an electric vehicle charging ecosystem. .- Decision Support System for the Monitoring and Risk Analysis of National Critical Entities. .- GNSS signal monitoring and security of supply of GNSS-based services. .- Surveillance of Offshore Installations with Patrol Routine. .- Relationships between Security Management and Technical Security of Norwegian Energy Enti-ties. .- Climate Change Risk Framework Using Complex Interdependent Critical Systems. .- Emergency resilience closer to citizen´s understanding. .- Development of Easy Risk Assessment Tool for Factory Cybersecurity. .- Adoption of Explainable Artificial Intelligence, to protect key decision processes from infor-mation manipulations and disorders.