CVE-2023-42804 in BigBlueButton
Summary
by MITRE • 10/30/2023
BigBlueButton is an open-source virtual classroom. BigBlueButton prior to version 2.6.0-beta.1 has a path traversal vulnerability that allows an attacker with a valid starting folder path, to traverse and read other files without authentication, assuming the files have certain extensions (txt, swf, svg, png). In version 2.6.0-beta.1, input validation was added on the parameters being passed and dangerous characters are stripped. There are no known workarounds.
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Analysis
by VulDB Data Team • 11/24/2023
The vulnerability identified as CVE-2023-42804 affects BigBlueButton, an open-source virtual classroom platform that facilitates online education and collaboration. This path traversal vulnerability represents a significant security flaw that undermines the platform's file access controls and data protection mechanisms. The vulnerability exists in versions prior to 2.6.0-beta.1 and allows unauthorized access to sensitive files through improper input validation. Attackers can exploit this weakness by manipulating file path parameters to access files outside of the intended directory structure, potentially compromising the confidentiality of educational content and system resources.
The technical flaw stems from insufficient validation of user-supplied input parameters that control file access operations within the BigBlueButton application. When users provide file paths for content retrieval, the system fails to properly sanitize or validate these inputs before processing them. This allows attackers to inject malicious path traversal sequences that bypass normal access controls. The vulnerability specifically targets files with extensions including txt, swf, svg, and png, indicating that the attack surface is limited to certain file types but still represents a substantial risk to the platform's security posture. The affected system processes these file paths without adequate sanitization, enabling attackers to navigate the file system beyond the designated boundaries.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can potentially expose sensitive educational materials, configuration files, and system resources that should remain protected. Attackers could access presentation files, user data, system logs, and other confidential information that might contain personal identifiers, educational content, or system configurations. The vulnerability's exploitation does not require authentication, meaning any user with access to the platform could potentially leverage this weakness. This creates a significant risk for educational institutions that rely on BigBlueButton for virtual learning environments, as it could lead to data breaches, privacy violations, and potential compliance issues with educational data protection regulations.
The remediation for CVE-2023-42804 involves upgrading to BigBlueButton version 2.6.0-beta.1 or later, where input validation has been implemented to strip dangerous characters from parameters. This fix addresses the root cause by properly sanitizing user inputs before they are processed for file access operations. Organizations should immediately implement this upgrade as there are no known workarounds for the vulnerability. Security teams should conduct thorough assessments of their BigBlueButton deployments to ensure all instances have been updated and verify that no unauthorized access has occurred. The implementation of proper input validation aligns with security best practices and helps prevent similar vulnerabilities from occurring in the future. This vulnerability demonstrates the importance of proper parameter validation and input sanitization in web applications, particularly in environments handling sensitive educational data. The fix represents a defensive programming approach that prevents path traversal attacks by eliminating dangerous characters from user inputs, thereby protecting the application's file system access controls.