CVE-2019-1003000 in Script Security Plugin
Summary
by MITRE
A sandbox bypass vulnerability exists in Script Security Plugin 2.49 and earlier in src/main/java/org/jenkinsci/plugins/scriptsecurity/sandbox/groovy/GroovySandbox.java that allows attackers with the ability to provide sandboxed scripts to execute arbitrary code on the Jenkins master JVM.
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Analysis
by VulDB Data Team • 11/26/2024
The vulnerability identified as CVE-2019-1003000 represents a critical sandbox bypass flaw in the Script Security Plugin for Jenkins, specifically affecting versions 2.49 and earlier. This vulnerability resides within the GroovySandbox.java file and fundamentally undermines the security model designed to isolate potentially malicious scripts executed within the Jenkins environment. The issue arises from inadequate validation mechanisms that fail to properly enforce sandbox restrictions, creating a pathway for privilege escalation attacks. The vulnerability is particularly dangerous because it allows attackers with minimal privileges to execute arbitrary code on the Jenkins master JVM, effectively compromising the entire build infrastructure. This represents a severe violation of the principle of least privilege that should govern all Jenkins operations and undermines the trust model that security-conscious organizations rely upon.
The technical implementation flaw stems from insufficient sandbox enforcement in the Groovy scripting environment used by Jenkins. Attackers can exploit this vulnerability by crafting malicious scripts that leverage specific Groovy features or reflection mechanisms to bypass the intended security boundaries. The vulnerability operates at the core of Jenkins' security architecture, where the sandbox is supposed to prevent access to dangerous Java classes and methods. However, the flaw allows attackers to manipulate the sandbox behavior through carefully constructed script inputs that can access the underlying JVM runtime. This bypass occurs due to improper handling of method calls and object instantiation within the sandboxed environment, enabling attackers to execute code with the same privileges as the Jenkins master process. The vulnerability is classified under CWE-250 as "Execute Code with Unusual or Unconventional Privilege" and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Groovy" in lateral movement and privilege escalation scenarios.
The operational impact of this vulnerability is catastrophic for organizations relying on Jenkins for continuous integration and deployment operations. Successful exploitation enables attackers to execute arbitrary commands on the Jenkins master, potentially leading to complete system compromise. Attackers can leverage this vulnerability to access sensitive build artifacts, steal credentials stored in Jenkins, modify build processes, or establish persistence within the infrastructure. The vulnerability affects organizations of all sizes, from small development teams to large enterprises, as Jenkins remains one of the most widely used continuous integration platforms. The attack vector is particularly concerning because it requires minimal privileges - attackers only need the ability to provide sandboxed scripts, which is often granted to developers or CI/CD pipeline creators. This makes the vulnerability extremely difficult to detect and prevent, as it can be exploited through legitimate Jenkins functionality. The impact extends beyond immediate system compromise to include potential data breaches, supply chain attacks, and disruption of critical build processes that organizations depend upon for software delivery.
Organizations must immediately implement mitigations to address this vulnerability through comprehensive patching strategies and operational security measures. The primary recommendation involves upgrading the Script Security Plugin to version 2.50 or later, where the sandbox bypass has been properly addressed. Additionally, administrators should implement strict access controls and privilege management, ensuring that only trusted individuals can submit scripts to Jenkins. Network segmentation and monitoring should be enhanced to detect suspicious script execution patterns, particularly those involving reflection or dynamic code loading. The vulnerability highlights the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies. Organizations should also consider implementing additional security controls such as script approval workflows, automated code scanning, and regular security assessments of Jenkins configurations. The remediation process should include comprehensive testing to ensure that the patch does not introduce compatibility issues with existing Jenkins jobs and plugins. Regular security training for development teams on secure coding practices and the dangers of executing untrusted scripts is essential to prevent exploitation through social engineering or insider threats. This vulnerability serves as a stark reminder of the critical importance of maintaining secure development practices and the potential consequences of insufficient sandbox enforcement in enterprise CI/CD environments.