Why Not Mitigate Vulnerabilities in Helm Charts?

[Context]: Containerization ensures the resilience of distributed applications by Kubernetes. Helm is a package manager for Kubernetes applications. A Helm package, namely "Chart'', is a set of pre-configured resources that one could quickly deploy a complex application. However, Helm broadens the attack surface of the distributed applications. [Objective]: This study aims to investigate the prevalence of fixable vulnerabilities, the factors related to the vulnerabilities, and current mitigation strategies in Helm Charts. [Method]: We conduct a mixed-methods study on 11,035 Helm Charts affected by 10,982 fixable vulnerabilities. We analyze the complexity of Charts and compare the distribution of vulnerabilities between official and unofficial Charts. Subsequently, we investigate vulnerability mitigation strategies from the Chart-associated repositories by a grounded theory. [Results]: Our findings highlight that the complexity of a Chart correlates with the number of vulnerabilities, and the official Charts do not contain fewer vulnerabilities compared to unofficial Charts. The 10,982 fixable vulnerabilities are at a median of high severity and can be easily exploited. In addition, we identify 11 vulnerability mitigation strategies in three categories. Due to the complexity of Charts, maintainers are required to investigate where a vulnerability impacts and how to mitigate it. The use of automated strategies is low as automation has limited capability(e.g., a higher number of false positives) in such complex Charts. [Conclusion]: There exists need for automation tools that assist maintainers in mitigating vulnerabilities to reduce manual effort. In addition, Chart maintainers lack incentives to mitigate vulnerabilities, given a lack of guidelines for mitigation responsibilities. Adopting a shared responsibility model in the Helm ecosystem would increase its security.