Mohamed Bilel Besbes

Kawsar Ahmed Bhuiyan, Mohamed Bilel Besbes, Rachna Raj et al.

Modern software development relies heavily on open-source components. Reusing components accelerates innovation but increases exposure to supply-chain attacks exploiting known vulnerabilities. Software Bills of Materials (SBOMs) improve software supply chain transparency by enumerating components, their versions, and their provenance. GitHub, the largest open-source development hosting platform, now automatically generates SBOMs for repositories, providing valuable metadata for risk assessment. Yet, it is unclear whether GitHub SBOMs can serve as a reliable source for vulnerability and license analysis, and how incomplete or inconsistent metadata may affect different programming ecosystems. To address this, we conduct a large-scale analysis of 10,000 GitHub repositories across ten programming language ecosystems, evaluating GitHub SBOMs against three other popular SBOM generators: Syft, Trivy, and the Microsoft SBOM Tool. Our study finds a lack of NTIA compliance in GitHub SBOMs, though core metadata is consistently present. We also find that component version and license information availability is highly dependent on the programming ecosystem. Compared with the other three tools, GitHub yields results similar to the Microsoft SBOM Tool and often outperforms Syft and Trivy in providing version and license information. Finally, we discuss potential shortcomings of the GitHub SBOM Tool, directly related to how each ecosystem manages its dependencies.

Mohamed Bilel Besbes, Gregory Mierzwinski, Suhaib Mujahid et al.

Software performance regressions can have significant business consequences, making automated detection a critical component of modern continuous integration pipelines. At Mozilla, performance anomaly detection is handled by Perfherder, Mozilla's performance engineering management system that relies on a Student's T-test-based approach to flag regressions across hundreds of daily code changes. However, our preliminary analysis of one year of Mozilla performance data reveals that 12.5% of generated alert groups are false positives, while approximately 6.8% of them contain regressions missed by the automated system. This paper presents an empirical study evaluating 25 change-point detection (CPD) methods and 15 ensemble approaches as alternatives to Mozilla's current method. We construct a ground-truth dataset of 174 performance time series manually annotated by eleven Mozilla performance engineers, representing one of the first practitioner-annotated CPD benchmarks for performance engineering. Our results show that while offline and hybrid CPD methods improve recall over Mozilla's method, they do so at a high cost to precision. Ensemble voting strategies alleviate this trade-off and offer more consistent performance, resulting in 11% improvement in the F1-score. We validate the experimental results through a practitioner survey and report on lessons learned from integrating the best methods into Mozilla's performance engineering system.