CVE-2020-2139 in Cobertura Plugin
Summary
by MITRE
An arbitrary file write vulnerability in Jenkins Cobertura Plugin 1.15 and earlier allows attackers able to control the coverage report file contents to overwrite any file on the Jenkins master file system.
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Analysis
by VulDB Data Team • 03/10/2020
The vulnerability identified as CVE-2020-2139 represents a critical arbitrary file write flaw within the Jenkins Cobertura Plugin version 1.15 and earlier releases. This issue arises from insufficient input validation and sanitization mechanisms within the plugin's processing of coverage report files, creating a pathway for malicious actors to manipulate the file system of the Jenkins master server. The vulnerability specifically affects environments where Jenkins is configured to process Cobertura coverage reports, making it particularly relevant for continuous integration and delivery pipelines that rely on code coverage analysis. The flaw exists in the plugin's handling of user-provided data during the report generation and processing phases, where attacker-controlled inputs are not properly validated before being used to determine file paths or content destinations.
The technical exploitation of this vulnerability occurs when an attacker can influence the contents of a coverage report file that the Cobertura plugin processes. Since the plugin does not adequately validate file paths or sanitize input data, an attacker who can upload or modify coverage report files can specify arbitrary file paths that the plugin will attempt to write to on the Jenkins master server. This allows for overwrite operations on any file within the Jenkins master file system, potentially enabling attackers to modify critical configuration files, inject malicious code into build processes, or compromise the integrity of the entire CI/CD pipeline. The vulnerability falls under CWE-937, which addresses the weakness of insufficient input validation, and aligns with ATT&CK technique T1059.001 for command and script injection, as the compromised system could be leveraged to execute arbitrary commands through modified configuration files or build scripts.
The operational impact of CVE-2020-2139 extends beyond immediate file system compromise, as it can lead to complete system takeover and persistent backdoor establishment within Jenkins environments. Attackers can exploit this vulnerability to modify Jenkins configuration files, inject malicious build steps, or replace critical binaries with compromised versions, potentially affecting multiple projects and builds across the organization. The vulnerability is particularly dangerous in multi-tenant Jenkins environments where multiple teams share the same master server, as a single compromised project could provide attackers with access to the entire Jenkins infrastructure. Organizations using Jenkins with the affected Cobertura plugin versions face significant risk of supply chain attacks, as compromised build processes could affect downstream systems and deployments. The vulnerability also impacts compliance and audit requirements, as it creates potential data integrity issues and provides attackers with means to hide their activities through file modification.
Mitigation strategies for CVE-2020-2139 focus on immediate plugin updates and access control measures. Organizations should upgrade to Jenkins Cobertura Plugin version 1.16 or later, which includes proper input validation and sanitization mechanisms. Additionally, implementing strict access controls and least privilege principles for Jenkins master server access can limit the potential impact of exploitation. Regular security scanning of Jenkins plugins and configurations should be enforced, with particular attention to plugin versions and their known vulnerabilities. Network segmentation and monitoring of file system access patterns can help detect potential exploitation attempts. Organizations should also implement proper code review processes for coverage report generation and establish incident response procedures specifically addressing CI/CD pipeline compromises. The vulnerability demonstrates the importance of maintaining up-to-date security practices in continuous integration environments, as these systems often serve as critical entry points for broader organizational attacks. Security teams should consider implementing automated vulnerability scanning tools that can identify and alert on outdated or vulnerable plugins within Jenkins installations, reducing the window of exposure for such critical flaws.