Policy-driven Software Bill of Materials on GitHub: An Empirical Study

Background. The Software Bill of Materials (SBOM) is a machine-readable list of all the software dependencies included in a software. SBOM emerged as way to assist securing the software supply chain. However, despite mandates from governments to use SBOM, research on this artifact is still in its early stages. Aims. We want to understand the current state of SBOM in open-source projects, focusing specifically on policy-driven SBOMs, i.e., SBOM created to achieve security goals, such as enhancing project transparency and ensuring compliance, rather than being used as fixtures for tools or artificially generated for benchmarking or academic research purposes. Method. We performed a mining software repository study to collect and carefully select SBOM files hosted on GitHub. We analyzed the information reported in policy-driven SBOMs and the vulnerabilities associated with the declared dependencies by means of descriptive statistics. Results. We show that only 0.56% of popular GitHub repositories contain policy-driven SBOM. The declared dependencies contain 2,202 unique vulnerabilities, while 22% of them do not report licensing information. Conclusion. Our findings provide insights for SBOM usage to support security assessment and licensing.