CVE-2020-12112 in BigBlueButton
Summary
by MITRE
BigBlueButton before 2.2.5 allows remote attackers to obtain sensitive files via Local File Inclusion.
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Analysis
by VulDB Data Team • 04/24/2020
BigBlueButton is an open source web conferencing system designed for online learning and virtual meetings that has been widely adopted in educational institutions and corporate environments. The vulnerability described in CVE-2020-12112 represents a critical local file inclusion flaw that affects versions prior to 2.2.5, creating a significant security risk for organizations relying on this platform for sensitive educational and business communications. This vulnerability falls under the Common Weakness Enumeration category CWE-22, which specifically addresses Improper Limitation of a Pathname to a Restricted Directory, commonly known as Path Traversal or Directory Traversal attacks. The flaw occurs when the application fails to properly validate and sanitize user-supplied input that is used to construct file paths, allowing attackers to manipulate the system into accessing files outside of intended directories.
The technical exploitation of this vulnerability involves attackers sending malicious requests that include directory traversal sequences such as ../ or ..\ in file path parameters. When the vulnerable BigBlueButton application processes these inputs without proper validation, it can be coerced into reading arbitrary files from the server filesystem. This includes sensitive configuration files, database credentials, application source code, and potentially system files that contain confidential information. The impact extends beyond simple information disclosure, as attackers could potentially access authentication tokens, encryption keys, or other critical system components that would allow for further compromise of the platform and underlying infrastructure. Attackers might also be able to read configuration files that contain database connection strings, which could lead to database access and potential data breaches.
The operational impact of this vulnerability is severe for educational institutions and organizations using BigBlueButton for virtual classrooms, meetings, and collaborative workspaces. A successful exploitation could result in unauthorized access to student records, proprietary business information, meeting transcripts, and other sensitive materials. The vulnerability is particularly dangerous in cloud environments where multiple organizations may share the same infrastructure, as attackers could potentially access files from other tenants. This flaw also enables attackers to escalate their privileges and potentially gain full control over the affected system, especially if they can access system configuration files or application logs that contain administrative credentials. The vulnerability affects the core functionality of the platform and could disrupt services while simultaneously creating opportunities for data exfiltration and persistent access.
Organizations should immediately upgrade to BigBlueButton version 2.2.5 or later to remediate this vulnerability, as this represents the official patch release that addresses the local file inclusion flaw. Additionally, implementing proper input validation and sanitization measures can help mitigate the risk even before applying the official patch, including implementing strict path validation, using allowlists for acceptable file paths, and employing secure coding practices that prevent user input from directly influencing file system operations. Network segmentation and firewall rules should be implemented to limit access to the BigBlueButton application, while monitoring systems should be configured to detect suspicious file access patterns and anomalous requests. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other components of the organization's IT infrastructure, as this vulnerability demonstrates the importance of proper input validation and secure coding practices across all applications. The ATT&CK framework categorizes this type of vulnerability under T1083 - File and Directory Discovery, which represents the reconnaissance phase that attackers often perform before executing more sophisticated attacks, making early detection and remediation crucial for maintaining organizational security posture.