CVE-2016-3721 in Jenkins
Summary
by MITRE
CloudBees Jenkins before 2.3 and LTS before 1.651.2 might allow remote authenticated users to inject arbitrary build parameters into the build environment via environment variables.
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Analysis
by VulDB Data Team • 07/03/2024
The vulnerability identified as CVE-2016-3721 affects CloudBees Jenkins versions prior to 2.3 and LTS versions prior to 1.651.2, representing a significant security flaw in continuous integration and deployment systems. This issue resides in the parameter injection mechanism within Jenkins build environments, where authenticated users can manipulate build parameters through environment variable manipulation. The flaw stems from insufficient input validation and sanitization of environment variables that are passed to build processes, creating a pathway for malicious parameter injection that could compromise the integrity of automated build workflows.
The technical implementation of this vulnerability involves the improper handling of environment variables during build execution processes. When Jenkins processes build parameters, it fails to adequately validate or sanitize environment variables that may contain user-controlled input. This weakness allows authenticated attackers to inject arbitrary build parameters into the build environment by manipulating environment variables, potentially leading to unauthorized code execution or data manipulation within the build system. The vulnerability specifically impacts Jenkins' parameter handling mechanisms, where environment variables are not properly filtered or escaped before being processed by the build engine, creating a direct injection vector.
From an operational perspective, this vulnerability poses substantial risks to organizations relying on Jenkins for automated build and deployment processes. Attackers with authenticated access can exploit this flaw to inject malicious parameters that may alter build behavior, execute unintended commands, or access sensitive system resources. The impact extends beyond simple parameter injection, as it could enable attackers to manipulate build outputs, compromise build integrity, or potentially escalate privileges within the Jenkins environment. This vulnerability is particularly dangerous in environments where Jenkins is used for production deployments, as it could lead to compromised software releases or unauthorized system modifications.
The vulnerability aligns with CWE-74, which describes "Improper Neutralization of Special Elements in Output Used by a Downstream Component," and relates to ATT&CK technique T1059.001 for command and scripting interpreter execution. Organizations should immediately implement the recommended patches for Jenkins versions 2.3 and LTS 1.651.2 to address this issue. Additional mitigations include restricting Jenkins user permissions, implementing strict environment variable validation, and monitoring build parameter changes. Security teams should also consider implementing network segmentation, access controls, and regular security audits of Jenkins configurations to prevent unauthorized access and parameter manipulation. The vulnerability demonstrates the critical importance of input validation in CI/CD systems and highlights the need for comprehensive security measures in automated build environments.