CVE-2017-1000107 in Jenkins
Summary
by MITRE
Script Security Plugin did not apply sandboxing restrictions to constructor invocations via positional arguments list, super constructor invocations, method references, and type coercion expressions. This could be used to invoke arbitrary constructors and methods, bypassing sandbox protection.
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Analysis
by VulDB Data Team • 11/22/2019
The Script Security Plugin vulnerability identified as CVE-2017-1000107 represents a critical sandboxing bypass issue within Jenkins automation server environments. This vulnerability specifically targets the plugin's handling of constructor invocations and method references, creating a pathway for attackers to circumvent security restrictions that are meant to contain script execution within safe boundaries. The flaw exists in how the plugin processes positional arguments lists, super constructor invocations, method references, and type coercion expressions, all of which are commonly used in scripting languages like Groovy that Jenkins supports for pipeline definitions and script execution.
The technical implementation of this vulnerability stems from insufficient validation of constructor and method invocation patterns within the plugin's security framework. When Jenkins processes scripts containing these specific expression types, the Script Security Plugin fails to properly enforce sandbox restrictions that would normally prevent access to sensitive system resources or arbitrary code execution. This occurs because the plugin's security model does not adequately account for the dynamic nature of constructor invocation through positional arguments, nor does it properly restrict super constructor calls that could potentially access parent class methods or constructors with elevated privileges. The vulnerability particularly affects scenarios where method references are used in conjunction with type coercion operations, creating additional attack vectors that bypass the intended security boundaries.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass full system compromise potential. An attacker with the ability to submit or modify Jenkins scripts could leverage this vulnerability to execute arbitrary constructors and methods, potentially gaining access to system resources, file systems, or network interfaces that should be restricted. This bypass of sandbox protections means that malicious scripts could access sensitive data, execute unauthorized commands, or establish persistence mechanisms within the Jenkins environment. The vulnerability is particularly concerning in enterprise settings where Jenkins serves as a central automation hub, as successful exploitation could provide attackers with access to build servers, source code repositories, and deployment pipelines that are critical to organizational operations.
Mitigation strategies for CVE-2017-1000107 should focus on immediate plugin updates to versions that properly address the sandboxing bypass conditions. Organizations must ensure that all Jenkins instances running Script Security Plugin are updated to versions that implement proper validation of constructor invocations and method references, particularly those involving positional arguments, super constructors, method references, and type coercion expressions. Security teams should also implement additional monitoring of script execution within Jenkins environments, particularly focusing on unusual constructor invocations or method calls that deviate from standard pipeline patterns. The vulnerability aligns with CWE-749 and CWE-252 categories related to exposed dangerous methods and improper restriction of operations within a security sandbox. From an ATT&CK perspective, this vulnerability maps to techniques involving privilege escalation and persistence through script-based attacks, specifically targeting the T1059.001 and T1078 sub-techniques related to command and script execution and valid accounts respectively. Organizations should also consider implementing additional security controls such as restricted user permissions, script approval processes, and regular security audits of Jenkins configurations to prevent exploitation of similar sandbox bypass vulnerabilities in other components of their automation infrastructure.