This book constitutes the thoroughly refereed post-conference proceedings of the 4th International Workshop on the Security of Industrial Control Systems and Cyber-Physical Systems, Cyber ICPS 2018, and the Second International Workshop on Security and Privacy Requirements Engineering, SECPRE 2018, held in Barcelona, Spain, in September 2018, in conjunction with the 23rd European Symposium on Research in Computer Security, ESORICS 2018.The Cyber ICPS Workshop received 15 submissions from which 8 full papers were selected for presentation. They cover topics related to threats, vulnerabilities and risks that cyber-physical systems and industrial control systems face; cyber attacks that may be launched against such systems; and ways of detecting and responding to such attacks. From the SECPRE Workshop 5 full papers out of 11 submissions are included. The selected papers deal with aspects of security and privacy requirements assurance and evaluation; and security requirements elicitation and modelling.