CVE-2018-1000862 in Jenkins
Summary
by MITRE
An information exposure vulnerability exists in Jenkins 2.153 and earlier, LTS 2.138.3 and earlier in DirectoryBrowserSupport.java that allows attackers with the ability to control build output to browse the file system on agents running builds beyond the duration of the build using the workspace browser.
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Analysis
by VulDB Data Team • 04/19/2020
This vulnerability resides in Jenkins version 2.153 and earlier, as well as LTS 2.138.3 and earlier, specifically within the DirectoryBrowserSupport.java component. The flaw represents an information exposure vulnerability that fundamentally compromises the security boundaries between build processes and the underlying file system. Attackers who can influence build output or control build parameters can exploit this weakness to traverse the file system on build agents beyond the normal build execution timeframe. The vulnerability essentially allows unauthorized file system enumeration and access to sensitive data that should remain isolated within the build environment. This issue directly impacts the principle of least privilege by enabling attackers to gain visibility into system resources that they should not normally be able to access during or after build processes.
The technical implementation of this vulnerability stems from inadequate access controls within the workspace browser functionality. When Jenkins processes builds, it creates workspace directories that typically should be isolated from external access once the build completes. However, the DirectoryBrowserSupport.java component fails to properly enforce these boundaries, allowing persistent access to the file system through the workspace browser interface. This flaw enables attackers to navigate beyond the typical build workspace constraints and potentially access sensitive system files, configuration data, or other resources that may contain confidential information. The vulnerability operates at the application layer and can be exploited through the Jenkins web interface, making it particularly dangerous as it requires minimal privileges to potentially access system resources.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable more sophisticated attacks that leverage the exposed file system access. An attacker who successfully exploits this vulnerability could potentially access build artifacts, source code repositories, configuration files containing credentials, or other sensitive data stored on the build agents. The persistence of this access beyond the build duration means that attackers can maintain access to system resources long after the initial compromise, creating opportunities for extended reconnaissance and data exfiltration. This vulnerability particularly affects organizations that rely on Jenkins for continuous integration and deployment processes, where build agents often contain sensitive information and credentials necessary for system operations.
Organizations should immediately upgrade to Jenkins versions 2.154 or later, or LTS 2.138.4 and later to remediate this vulnerability. The fix addresses the improper access controls in DirectoryBrowserSupport.java by implementing proper boundary enforcement for workspace browsing functionality. Administrators should also review and restrict access to Jenkins build agents, implementing least privilege principles for build execution environments. Additionally, organizations should monitor build agent file systems for unauthorized access patterns and implement network segmentation to limit exposure of build agents to untrusted networks. This vulnerability aligns with CWE-200 (Information Exposure) and could potentially be leveraged as part of broader attack chains targeting Jenkins environments, making it a critical security concern for organizations using continuous integration systems. The ATT&CK framework categorizes this vulnerability under credential access and reconnaissance techniques, as it enables attackers to gather information about system resources and potentially extract sensitive data from build environments.