D5.1 Physical layer threat modelling

This deliverable, part of the NATWORK project, presents a comprehensive framework for threat modelling at the physical layer of next-generation wireless systems, particularly in the context of 5G and emerging 6G technologies.The report begins by analysing existing threat models and methodologies relevant to the physical layer. Notably, it examines the IEEE SA P3349 Secure-by-Component approach, which emphasizes decomposing complex communication systems into secure, modular building blocks. The ISO/IEC 27005 risk management framework is also reviewed for its systematic process of identifying, assessing, and mitigating risks. Furthermore, the O-RAN Security Threat Modelling and Risk Assessment is considered, highlighting the relevance of open, disaggregated network architectures to PHY layer vulnerabilities.Informed by these foundations, the deliverable defines the NATWORK Physical Layer Threat Modelling Methodology. This methodology builds upon recognised best practices but extends them to capture the evolving threat landscape of 5G/6G networks, characterized by virtualization, multi-vendor environments, AI-enhanced signal processing, and advanced physical-layer technologies like Reconfigurable Intelligent Surfaces and Massive MIMO. The methodology aligns with secure-by-design principles and emphasizes a proactive, adaptive approach to mitigating risks at the physical layer.The core of the deliverable is the application of this methodology to develop the NATWORK Physical Layer Threat Model. The model systematically identifies key assets, potential adversaries, and vulnerabilities, followed by a threat characterisation across four primary categories: jamming, eavesdropping, spoofing, and physical tampering. The report presents a detailed analysis of vulnerabilities, distinguishing between those inherent to protocols and standards, technology-specific risks (such as those related to RIS and MIMO), and emerging AI-driven threats that exploit PHY-layer identifiers or control signals.Furthermore, the report incorporates a layered risk and impact assessment that considers both the likelihood of threat occurrence and the potential consequences for system confidentiality, integrity, and availability. This assessment provides a clear basis for prioritising mitigation efforts across different technologies and threat vectors.To address these challenges, the deliverable outlines key mitigation methods. Recommendations include established countermeasures, such as secure pilot authentication and beam randomization, as well as novel approaches targeting AI-assisted attacks and vulnerabilities introduced by virtualization and multi-vendor ecosystems. For RIS systems, the document proposes specific security controls for configuration integrity and unauthorised signal manipulation prevention. For MIMO systems, obfuscation and advanced signal processing techniques are discussed to strengthen resilience.In conclusion, this deliverable establishes a strategic foundation for adopting secure-by-design practices at the PHY layer. These practices are essential for realising the NATWORK project's vision of resilient, self-adaptive, and secure next-generation communication networks. Specifically, it directly supports Operational Objective #4: Provide Physical Layer Security that supports encryption-free, perennial self-resilience of wireless links. By addressing vulnerabilities early in the system design and development lifecycle, and by promoting the standardisation and harmonisation of security controls, NATWORK contributes to advancing Europe's leadership in secure, trustworthy 6G services.This report also lays the groundwork for future work within NATWORK, including validation of proposed mitigations, integration of threat modelling outcomes into system architecture, and continuous updates of the threat landscape to reflect technological advances and evolving adversarial tactics.