CVE-2017-1000110 in Jenkins
Summary
by MITRE
Blue Ocean allows the creation of GitHub organization folders that are set up to scan a GitHub organization for repositories and branches containing a Jenkinsfile, and create corresponding pipelines in Jenkins. It did not properly check the current user's authentication and authorization when configuring existing GitHub organization folders. This allowed users with read access to the GitHub organization folder to reconfigure it, including changing the GitHub API endpoint for the organization folder to an attacker-controlled server to obtain the GitHub access token, if the organization folder was initially created using Blue Ocean.
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Analysis
by VulDB Data Team • 11/22/2019
The vulnerability identified as CVE-2017-1000110 resides within the Blue Ocean plugin for Jenkins, a widely used continuous integration and delivery platform that provides a modern user interface for Jenkins operations. This security flaw specifically affects the plugin's handling of GitHub organization folder configurations, which is a core functionality that enables automated pipeline creation based on GitHub repository structures containing Jenkinsfile configurations. The vulnerability stems from inadequate authentication and authorization checks during the configuration modification process of existing GitHub organization folders, creating a significant privilege escalation vector within the Jenkins environment.
The technical flaw manifests when users with only read access to a GitHub organization folder can manipulate the folder's configuration settings through the Blue Ocean interface. This misconfiguration allows attackers to modify the GitHub API endpoint that the organization folder uses to communicate with GitHub services. The vulnerability is particularly dangerous because it enables unauthorized users to redirect the folder's communication to attacker-controlled servers, potentially capturing sensitive credentials including GitHub access tokens that are automatically stored within the Jenkins configuration. This represents a critical breakdown in the principle of least privilege, where read-only users can escalate their access to potentially full repository control through manipulation of the configuration parameters.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can lead to complete compromise of GitHub organization repositories and their associated Jenkins pipelines. An attacker who gains the ability to modify the GitHub API endpoint configuration can intercept authentication tokens, potentially gaining access to all repositories within the targeted organization. This vulnerability directly relates to CWE-284, which addresses improper access control, and can be mapped to ATT&CK technique T1552.001 for credentials in files, as the access tokens are stored in Jenkins configuration files that become accessible through this vulnerability. The attack chain typically involves initial access through a low-privilege account, followed by configuration manipulation to redirect API calls and extract credentials, potentially leading to complete organizational compromise.
Mitigation strategies for this vulnerability require immediate implementation of proper access controls and configuration management within Jenkins environments. Organizations should ensure that only authorized administrators have the ability to modify existing GitHub organization folder configurations, implementing role-based access controls that prevent read-only users from making configuration changes. The Jenkins security configuration should be reviewed to enforce proper authentication checks before allowing any modification of organization folder settings. Additionally, implementing network segmentation and monitoring for unusual API endpoint changes can help detect potential exploitation attempts. Regular security audits of Jenkins plugins and configurations should be conducted to identify similar access control weaknesses, and the Blue Ocean plugin should be updated to versions that address this specific vulnerability. Organizations should also consider implementing credential rotation policies and monitoring for unauthorized access token usage, as the vulnerability essentially allows for credential harvesting through configuration manipulation rather than direct authentication bypass.