CVE-2020-2117 in Pipeline GitHub Notify Step Plugin
Summary
by MITRE
A missing permission check in Jenkins Pipeline GitHub Notify Step Plugin 1.0.4 and earlier allows attackers with Overall/Read permission to connect to an attacker-specified URL using attacker-specified credentials IDs obtained through another method, capturing credentials stored in Jenkins.
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Analysis
by VulDB Data Team • 02/13/2020
The vulnerability described in CVE-2020-2117 represents a critical authorization bypass flaw within the Jenkins Pipeline GitHub Notify Step Plugin version 1.0.4 and earlier. This issue stems from a missing permission check that allows unprivileged users to exploit the plugin's functionality to make HTTP requests to arbitrary URLs using credentials stored within the Jenkins system. The vulnerability specifically affects users who possess only Overall/Read permission, which is typically considered a low-privilege access level in Jenkins security model.
The technical flaw manifests in the plugin's implementation where it fails to validate whether the requesting user has adequate authorization to perform the specific action of making HTTP requests to external endpoints. This missing validation occurs during the execution of the GitHub notify step within Jenkins pipelines, where the plugin accepts user-provided parameters including target URLs and credential identifiers. The vulnerability creates a path where an attacker with minimal privileges can leverage the plugin to establish connections to attacker-controlled servers, potentially capturing sensitive authentication data stored in Jenkins.
From an operational perspective, this vulnerability poses significant risks to Jenkins environments as it enables attackers to perform credential harvesting attacks without requiring elevated privileges. The impact extends beyond simple information disclosure, as captured credentials could potentially be used to access other systems or services that rely on the same authentication mechanisms. Attackers could use this vulnerability to target Jenkins instances that store credentials for external services, databases, or cloud platforms, effectively expanding their attack surface. The vulnerability's exploitation requires only the ability to create or modify Jenkins pipelines, which is often more accessible than higher privilege levels.
The weakness aligns with CWE-284, which describes insufficient access control mechanisms, specifically focusing on inadequate permission checks in software components. This vulnerability also maps to ATT&CK technique T1555.003, which covers credential access through the use of stolen credentials, as the flaw enables unauthorized access to stored credentials within Jenkins. Additionally, the vulnerability demonstrates characteristics of privilege escalation through indirect means, as it allows low-privilege users to effectively bypass access controls.
Mitigation strategies for this vulnerability should include immediate upgrade to Jenkins Pipeline GitHub Notify Step Plugin version 1.0.5 or later, which contains the necessary permission checks. Organizations should also implement strict access controls and privilege management within their Jenkins environments, ensuring that only authorized personnel have the ability to create or modify pipeline configurations. Network-level restrictions can be applied to limit outbound connections from Jenkins instances, particularly to prevent access to potentially malicious endpoints. Regular security auditing of Jenkins plugins and configurations should be conducted to identify similar permission bypass vulnerabilities. Implementing Jenkins security best practices including role-based access control, credential rotation, and monitoring for unusual pipeline activity can further reduce the risk exposure associated with this vulnerability.