CVE-2019-10394 in Script Security Plugin
Summary
by MITRE
A sandbox bypass vulnerability in Jenkins Script Security Plugin 1.62 and earlier related to the handling of property names in property expressions on the left-hand side of assignment expressions allowed attackers to execute arbitrary code in sandboxed scripts.
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Analysis
by VulDB Data Team • 08/22/2020
The vulnerability identified as CVE-2019-10394 represents a critical sandbox bypass flaw within the Jenkins Script Security Plugin affecting versions 1.62 and earlier. This issue stems from inadequate validation of property names within property expressions that appear on the left-hand side of assignment operations, creating a pathway for malicious actors to circumvent the security restrictions imposed by the sandbox environment. The flaw specifically targets the plugin's handling of dynamic property assignments, where the system fails to properly sanitize or validate the identifiers used in these contexts.
The technical implementation of this vulnerability exploits the manner in which Jenkins processes property expressions during script execution. When a script contains an assignment operation where the left-hand side consists of a property expression, the plugin's security mechanisms should prevent access to restricted methods or classes. However, the flaw allows attackers to manipulate property names in ways that bypass these protections, effectively granting unauthorized code execution capabilities within the sandboxed environment. This represents a fundamental failure in the plugin's input validation and privilege separation mechanisms.
From an operational standpoint, this vulnerability poses significant risks to Jenkins environments that rely on the Script Security Plugin for protecting against malicious script execution. Attackers exploiting this flaw can execute arbitrary code with the privileges of the Jenkins user, potentially leading to complete system compromise, data exfiltration, or further lateral movement within the network. The impact extends beyond individual build servers to encompass entire CI/CD pipelines, as compromised Jenkins instances can serve as entry points for broader infrastructure attacks. Organizations using older versions of the plugin face substantial exposure given that this vulnerability allows for privilege escalation without requiring additional authentication or specialized attack vectors.
The vulnerability aligns with CWE-20, which addresses improper input validation, and demonstrates characteristics consistent with sandbox escape techniques that fall under the ATT&CK framework's T1059.007 (Command and Scripting Interpreter) and T1068 (Exploitation for Privilege Escalation) categories. Organizations should immediately upgrade to patched versions of the Script Security Plugin to address this issue, while implementing additional monitoring for suspicious script execution patterns. Network segmentation and least-privilege principles should be enforced to limit potential damage from exploitation, and regular security assessments should verify the integrity of Jenkins configurations and plugin installations.