ICT services are reshaped by evolving business models, which includes virtualization paradigms and integration with the physical environment. Multi-domain and complex business service chains bring more agility in service deployment and operation, but also introduce additional unsolved security and privacy issues. GUARD tackles conflicting trends in the cybersecurity market, like fragmentation or vendor lock-ins. It will develop an open modular, pluggable, extendable and scalable security framework for advanced assurance and protection of trustworthy and reliable business chains. Its purposes include: i) increase analysis and detection information base, while preserving privacy, ii) improve detection capabilities by data correlation between domains and sources, iii) verify reliability and dependability via formal methods that take into account configuration and trust properties of the whole chain, iv) increase awareness by better propagation of knowledge to the humans in the loop. Blending security-by-design with enhanced inspection and detection techniques will enable quick and effective reaction to cyber-threats. Demonstration and validation in two challenging scenarios are envisioned to bring the technology to an acceptable level of maturity.