CVE-2020-2120 in FitNesse Plugin
Summary
by MITRE
Jenkins FitNesse Plugin 1.30 and earlier does not configure the XML parser to prevent XML external entity (XXE) attacks.
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Analysis
by VulDB Data Team • 02/13/2020
The Jenkins FitNesse Plugin vulnerability CVE-2020-2120 represents a critical security flaw that exposes systems to XML external entity attacks. This vulnerability affects versions 1.30 and earlier of the FitNesse plugin for Jenkins, a widely used continuous integration and delivery platform. The issue stems from improper configuration of the XML parser within the plugin's processing logic, which fails to disable external entity resolution. This configuration oversight creates an attack surface where malicious actors can exploit the XML parser to execute unauthorized operations. The vulnerability is particularly concerning because it allows for potential data exfiltration, denial of service attacks, and privilege escalation within the Jenkins environment. The flaw exists at the parser configuration level where the plugin does not enforce secure XML processing practices that are fundamental to preventing XXE attacks.
The technical implementation of this vulnerability occurs when the FitNesse plugin processes XML data without properly setting the secure processing features of the underlying XML parser. Specifically, the plugin fails to configure the parser to disable external entity resolution, which is a core security measure recommended by the OWASP XML External Entity (XXE) Prevention Cheat Sheet. This misconfiguration allows attackers to craft malicious XML payloads that reference external resources or internal system files. When the plugin processes such XML content, the parser resolves these external entities, potentially leading to information disclosure, server-side request forgery, or even remote code execution depending on the Jenkins environment configuration. The vulnerability maps directly to CWE-611, which specifically addresses Improper Restriction of XML External Entity Reference, and aligns with ATT&CK technique T1213.002 for Data from Information Repositories. The lack of proper XML parser hardening means that any XML input processed by the plugin becomes a potential attack vector for malicious actors seeking to exploit the Jenkins infrastructure.
The operational impact of this vulnerability extends beyond simple data exposure, potentially compromising entire Jenkins environments and the CI/CD pipelines they support. Organizations using affected plugin versions face risks of unauthorized access to sensitive build artifacts, configuration files, and potentially system credentials stored within the Jenkins environment. Attackers could leverage this vulnerability to gain access to internal network resources, escalate privileges within the Jenkins instance, or extract confidential information from the XML-based data processing workflows. The vulnerability affects not only the immediate Jenkins instance but also any downstream systems that rely on the processed FitNesse data, creating cascading security risks throughout the development pipeline. Additionally, the impact is amplified in environments where Jenkins is used for automated testing, deployment, and integration workflows, as these processes may involve sensitive data handling and privileged operations that could be exploited through the XXE vulnerability.
Mitigation strategies for CVE-2020-2120 require immediate action to upgrade the FitNesse plugin to version 1.31 or later, which contains the necessary security fixes. Organizations should also implement comprehensive XML input validation and sanitization measures to reduce the risk of exploitation even in environments where upgrading is not immediately feasible. The recommended approach includes configuring XML parsers to disable external entity resolution, implementing proper input filtering, and establishing network segmentation to limit potential attack surfaces. Security teams should conduct thorough vulnerability assessments to identify all instances of the affected plugin within their Jenkins infrastructure and ensure that proper security configurations are applied. Additionally, implementing monitoring and logging for XML processing activities can help detect potential exploitation attempts. Organizations should also consider implementing web application firewalls and intrusion detection systems to provide additional layers of protection against XXE attack patterns. The fix addresses the core issue by ensuring that XML parsers are properly configured with secure processing features, aligning with industry best practices established in the OWASP Top Ten and NIST cybersecurity guidelines for secure software development practices.