CVE-2024-23901 in GitLab Branch Source Plugin
Summary
by MITRE • 01/24/2024
Jenkins GitLab Branch Source Plugin 684.vea_fa_7c1e2fe3 and earlier unconditionally discovers projects that are shared with the configured owner group, allowing attackers to configure and share a project, resulting in a crafted Pipeline being built by Jenkins during the next scan of the group.
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Analysis
by VulDB Data Team • 02/18/2024
The vulnerability identified as CVE-2024-23901 affects the Jenkins GitLab Branch Source Plugin version 684.vea_fa_7c1e2fe3 and earlier, presenting a significant security risk through improper access control mechanisms. This flaw enables attackers to exploit the plugin's project discovery behavior by configuring and sharing projects within the owner group, creating a scenario where maliciously crafted pipelines can be automatically built by Jenkins during subsequent group scans. The vulnerability stems from the plugin's unconditional discovery of shared projects without proper access validation, allowing unauthorized entities to manipulate the build process through project sharing configurations.
The technical implementation of this vulnerability resides in the GitLab Branch Source Plugin's handling of project discovery and access control. When Jenkins scans a GitLab group, it systematically discovers all projects shared with the configured owner group regardless of the user's actual permissions or authorization status. This behavior creates an attack surface where an attacker with access to the GitLab group configuration can share a malicious project and subsequently trigger the Jenkins pipeline execution. The vulnerability operates at the intersection of identity management and access control, where the plugin fails to validate whether the configured credentials have legitimate access rights to the discovered projects, creating a path for privilege escalation through project sharing manipulation.
The operational impact of CVE-2024-23901 extends beyond simple unauthorized access, as it enables attackers to execute arbitrary code within the Jenkins environment through crafted pipeline definitions. When Jenkins processes the shared project during its next scan cycle, it will automatically build the malicious pipeline, potentially leading to remote code execution, data exfiltration, or system compromise. This vulnerability directly impacts the principle of least privilege by allowing unauthorized project sharing to result in unauthorized build execution, effectively bypassing normal Jenkins security controls and access restrictions. The attack vector is particularly concerning because it requires minimal privileges to exploit, as the attacker only needs to configure project sharing rather than direct system access.
Mitigation strategies for this vulnerability should focus on immediate plugin version updates to the latest secure release, which addresses the unconditional project discovery behavior. Organizations should implement strict access controls and monitor GitLab group sharing configurations to prevent unauthorized project additions. The Jenkins security configuration should include regular audits of shared projects and implementation of additional validation checks before pipeline execution. This vulnerability aligns with CWE-284 Access Control Issues and maps to ATT&CK technique T1059 Command and Scripting Interpreter, as it enables attackers to execute malicious code through pipeline builds. Security teams should also consider implementing network segmentation and monitoring for unusual Jenkins build patterns that could indicate exploitation attempts, as well as establishing proper change management processes for GitLab group configurations to prevent unauthorized project sharing modifications.