*Article* **A Novel Model for Vulnerability Analysis through Enhanced Directed Graphs and Quantitative Metrics**

**Ángel Longueira-Romero 1,2,\*, Rosa Iglesias 1, Jose Luis Flores 1 and Iñaki Garitano 2**


**Abstract:** The rapid evolution of industrial components, the paradigm of Industry 4.0, and the new connectivity features introduced by 5G technology all increase the likelihood of cybersecurity incidents. Such incidents are caused by the vulnerabilities present in these components. Designing a secure system is critical, but it is also complex, costly, and an extra factor to manage during the lifespan of the component. This paper presents a model to analyze the known vulnerabilities of industrial components over time. The proposed Extended Dependency Graph (EDG) model is based on two main elements: a directed graph representation of the internal structure of the component, and a set of quantitative metrics based on the Common Vulnerability Scoring System (CVSS). The EDG model can be applied throughout the entire lifespan of a device to track vulnerabilities, identify new requirements, root causes, and test cases. It also helps prioritize patching activities. The model was validated by application to the OpenPLC project. The results reveal that most of the vulnerabilities associated with OpenPLC were related to memory buffer operations and were concentrated in the *libssl* library. The model was able to determine new requirements and generate test cases from the analysis.

**Keywords:** CPE; CVE; CVSS; CWE; CAPEC; directed graph; IACS; cybersecurity; vulnerability assessment; security metrics; IEC 62443; OpenPLC
