The information infrastructure – comprising computers, embedded devices, networks and software systems – is vital to operations in every sector: chemicals, commercial facilities, communications, critical manufacturing, dams, defense industrial base, emergency services, energy, financial services, food and agriculture, government facilities, healthcare and public health, information technology, nuclear reactors, materials and waste, transportation systems, and water and wastewater systems.  Global business and industry, governments, indeed society itself, cannot function if major components of the critical information infrastructure are degraded, disabled or destroyed.Critical Infrastructure Protection XV describes original research results and innovative applications in the interdisciplinary field of critical infrastructure protection.  Also, it highlights the importance of weaving science, technology and policy in crafting sophisticated, yet practical, solutions that willhelp secure information, computer and network assets in the various critical infrastructure sectors.  Areas of coverage include: Industrial Control Systems Security; Telecommunications Systems Security; Infrastructure Security. This book is the fourteenth volume in the annual series produced by the International Federation for Information Processing (IFIP) Working Group 11.10 on Critical Infrastructure Protection, an international community of scientists, engineers, practitioners and policy makers dedicated to advancing research, development and implementation efforts focused on infrastructure protection.  The book contains a selection of 13 edited papers from the Fifteenth Annual IFIP WG 11.10 International Conference on Critical Infrastructure Protection, held as a virtual event during the spring of 2021. Critical Infrastructure Protection XV is an important resource for researchers, faculty members and graduate students, as well as for policy makers, practitioners and other individuals with interests in homeland security.