CVE-2016-3102 in Script Security Plugin
Summary
by MITRE
The Script Security plugin before 1.18.1 in Jenkins might allow remote attackers to bypass a Groovy sandbox protection mechanism via a plugin that performs (1) direct field access or (2) get/set array operations.
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Analysis
by VulDB Data Team • 11/12/2022
The Script Security plugin in Jenkins prior to version 1.18.1 contained a critical vulnerability that undermined the core security protections designed to prevent unauthorized code execution within the Jenkins environment. This vulnerability specifically targeted the Groovy sandbox mechanism, which serves as a fundamental defense layer to restrict potentially dangerous operations when executing user-provided scripts. The flaw allowed attackers to bypass these protective measures through two distinct attack vectors that exploited weaknesses in the plugin's validation logic.
The technical implementation of this vulnerability involved two primary exploitation methods that leveraged direct field access and get/set array operations to circumvent the sandbox protections. When plugins attempted to access object fields directly rather than through proper method calls, or when they performed array operations that bypassed standard access controls, the sandbox mechanism failed to properly validate these operations. This occurred because the validation logic did not adequately account for these specific patterns of code execution that could still result in arbitrary code execution despite appearing benign. The vulnerability exploited the gap between what the sandbox considered safe operations and what it actually prevented, creating a pathway for attackers to execute malicious code within the Jenkins environment.
The operational impact of this vulnerability was significant as it allowed remote attackers to execute arbitrary code on Jenkins servers with the privileges of the Jenkins user. This could lead to complete system compromise, unauthorized access to build artifacts, data exfiltration, and potential lateral movement within the network. The vulnerability was particularly dangerous because it could be exploited through legitimate plugin mechanisms, making it difficult to detect and prevent through traditional security monitoring approaches. Organizations using Jenkins with vulnerable Script Security plugin versions faced a heightened risk of supply chain attacks, as malicious actors could potentially compromise plugins that would then be executed within the Jenkins environment.
Mitigation strategies for this vulnerability required immediate patching of the Script Security plugin to version 1.18.1 or later, which included enhanced validation logic to properly detect and block the problematic field access and array operation patterns. Organizations should also implement additional security controls such as restricting plugin installations to trusted sources, implementing proper access controls for Jenkins administrators, and monitoring for unusual plugin behavior or code execution patterns. The vulnerability aligns with CWE-250, which deals with executing code with elevated privileges, and maps to ATT&CK technique T1059.007 for executing commands through script interpreters, demonstrating how sandbox bypasses can lead to privilege escalation and persistent access within target environments. Regular security audits and vulnerability assessments should be conducted to identify similar gaps in other sandboxed environments and ensure proper implementation of access controls and code validation mechanisms.