CVE-2020-2146 in Mac Plugin
Summary
by MITRE
Jenkins Mac Plugin 1.1.0 and earlier does not validate SSH host keys when connecting agents created by the plugin, enabling man-in-the-middle attacks.
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Analysis
by VulDB Data Team • 03/10/2020
The vulnerability identified as CVE-2020-2146 affects Jenkins Mac Plugin versions 1.1.0 and earlier, presenting a critical security flaw that undermines the integrity of remote agent connections. This issue stems from the plugin's failure to properly validate SSH host keys during the establishment of connections between Jenkins master and Mac agents. The absence of host key validation creates an exploitable condition where attackers can intercept communications between the Jenkins server and its agents, potentially compromising the entire continuous integration and deployment pipeline.
The technical root cause of this vulnerability lies in the plugin's implementation of SSH connection handling without proper host key verification mechanisms. When Jenkins creates agents on Mac systems through this plugin, it establishes SSH connections that should verify the authenticity of the remote host's identity. However, the plugin fails to perform this critical validation step, allowing malicious actors to perform man-in-the-middle attacks by presenting forged SSH host keys. This flaw directly violates security best practices for SSH communications and represents a classic example of insufficient input validation and authentication checks.
The operational impact of CVE-2020-2146 extends far beyond simple network interception, as it enables attackers to gain unauthorized access to Jenkins environments and potentially compromise the entire software supply chain. An attacker who successfully executes a man-in-the-middle attack can intercept build artifacts, modify code during the build process, access sensitive configuration data, and potentially escalate privileges within the Jenkins environment. This vulnerability affects organizations that rely on Mac agents for their CI/CD pipelines, potentially exposing critical development infrastructure to unauthorized access and data compromise. The attack vector is particularly concerning because it operates at the network level during agent connection establishment, making it difficult to detect through traditional application-level security controls.
Organizations should immediately upgrade to Jenkins Mac Plugin version 1.1.1 or later, which includes the necessary host key validation mechanisms. System administrators should also implement additional security measures such as configuring SSH known_hosts files, enabling strict host key checking at the system level, and monitoring for unauthorized SSH connections. The vulnerability aligns with CWE-310, which addresses cryptographic issues related to insufficient validation of cryptographic signatures, and maps to ATT&CK technique T1566 for phishing with social engineering. Security teams should conduct comprehensive audits of their Jenkins configurations to ensure proper SSH host key validation is implemented across all agent types and connection methods. Additionally, implementing network segmentation and monitoring for unusual SSH traffic patterns can help detect potential exploitation attempts and provide early warning of security incidents.