Distinct from traditional malicious packages, this paper uncovers a novel attack vector named “blackhat Search Engine Optimization through REPositories (RepSEO)”. In this approach, attackers carefully craft packages to manipulate search engine results, exploiting the credibility of software repositories to promote illicit websites. Our research presents a systematic analysis of the underground ecosystem of RepSEO, identifying key players such as account providers, advertisers, and publishers. We developed an effective detection tool, applied to a ten-year large-scale dataset of npm, Docker Hub, and NuGet software repositories. This investigation led to the startling discovery of 3,801,682 abusive packages, highlighting the widespread nature of this attack. Our study also delves into the supply chain tactics of these attacks, revealing strategies like the use of self-hosted email services for account registration, redirection methods to obscure landing pages, and rapid deployment techniques by aggressive attackers. Additionally, we explore the profit motives behind these attacks, identifying two primary types of advertisers: survey-based advertisers and malware distribution advertisers. We reported npm, NuGet, and Docker Hub about the RepSEO packages and the related supply chain vulnerabilities of Google, and received their acknowledgments. Software repositories have started removing the abusive packages as of this paper's submission. We also opensource our code and data to facilitate future research.

Continuous Integration (CI) platforms have widely adopted caching to speed up CI task executions by storing and reusing dependent packages. Unfortunately, CI cache also exposes new attack surfaces when cache objects are shared across trust boundaries. In this paper, we systematically investigate potential security threats of CI cache features in seven mainstream CI platforms (CIPs). We find that existing CIPs have isolation issues in their cache sharing and inheritance strategies, potentially raising cache poisoning and data leakage problems. By exploiting these vulnerable mechanisms, we further uncover four attack vectors enabling attackers to stealthily inject malicious code into the cache or steal sensitive data. Even worse, many CIPs provide vulnerable official cache templates that will mistakenly store and expose sensitive data in the cache by default. To understand the potential impact of our disclosed threats, we develop an analysis tool and conduct a large-scale measurement on open-source repositories. Our measurement results show that many popular repositories are potentially affected by these attacks. We also identify 78 repositories that expose their high-value secrets in cache objects and are at risk of secret leakage. We have duly reported identified vulnerabilities to corresponding stakeholders and received positive responses.

Package registries host reusable code assets, allowing developers to share and reuse packages easily, thus accelerating the software development process. Current software registry ecosystems involve multiple independent stakeholders for package management. Unfortunately, abnormal behavior and information inconsistency inevitably exist, enabling adversaries to conduct malicious activities with minimal effort covertly. In this paper, we investigate potential security vulnerabilities in six popular software registry ecosystems. Through a systematic analysis of the official registries, corresponding registry mirrors and registry clients, we identify twelve potential attack vectors, with six of them disclosed for the first time, that can be exploited to distribute malicious code stealthily. Based on these security issues, we build an analysis framework, RScouter, to continuously monitor and uncover vulnerabilities in registry ecosystems. We then utilize RScouter to conduct a measurement study spanning one year over six registries and seventeen popular mirrors, scrutinizing over 4 million packages across 53 million package versions. Our quantitative analysis demonstrates that multiple threats exist in every ecosystem, and some have been exploited by attackers. We have duly reported the identified vulnerabilities to related stakeholders and received positive responses.