CVE-2020-5231 in Opencast
Summary
by MITRE
In Opencast before 7.6 and 8.1, users with the role ROLE_COURSE_ADMIN can use the user-utils endpoint to create new users not including the role ROLE_ADMIN. ROLE_COURSE_ADMIN is a non-standard role in Opencast which is referenced neither in the documentation nor in any code (except for tests) but only in the security configuration. From the name � implying an admin for a specific course � users would never expect that this role allows user creation. This issue is fixed in 7.6 and 8.1 which both ship a new default security configuration.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/27/2024
The vulnerability described in CVE-2020-5231 represents a significant privilege escalation flaw within the Opencast media management system. This issue affects versions prior to 7.6 and 8.1, where a specific security misconfiguration allows users with the non-standard ROLE_COURSE_ADMIN role to perform user creation actions through the user-utils endpoint. The vulnerability stems from the improper definition and implementation of access controls, creating an unexpected administrative capability that violates the principle of least privilege. The ROLE_COURSE_ADMIN role, while seemingly appropriate for course-level management, was not properly constrained in the security configuration, enabling it to bypass normal user creation restrictions that should typically be reserved for administrators with explicit administrative permissions.
The technical flaw manifests in the security configuration layer of Opencast where the ROLE_COURSE_ADMIN role was inadvertently granted permissions that extended beyond its intended scope. This misconfiguration allowed the role to access the user-utils endpoint without proper authorization checks, enabling unauthorized user creation capabilities. The vulnerability is particularly concerning because the ROLE_COURSE_ADMIN role was not documented or officially supported within the system, making it an unexpected and undocumented security boundary. The security configuration file contained references to this role but failed to properly restrict its capabilities, creating a path for privilege escalation. This flaw aligns with CWE-284, which addresses improper access control, and specifically demonstrates how inadequate security configuration can lead to unauthorized privilege elevation.
The operational impact of this vulnerability extends beyond simple user creation capabilities, as it enables potential attackers or malicious users with access to the ROLE_COURSE_ADMIN role to create new administrative accounts. This could lead to full system compromise, unauthorized access to sensitive media content, and potential data breaches. The vulnerability affects the integrity and confidentiality of the entire Opencast system, as unauthorized users could escalate their privileges and gain access to restricted administrative functions. The fact that this role was referenced only in security configuration files and not in documentation or code implementation suggests a lack of proper security review processes, potentially indicating broader security configuration issues within the system.
The mitigation for this vulnerability required the implementation of proper security configuration changes in Opencast versions 7.6 and 8.1. The fix involved updating the default security configuration to properly restrict the ROLE_COURSE_ADMIN role's capabilities and prevent it from accessing the user-utils endpoint. This resolution addresses the root cause by ensuring that only users with proper administrative roles can create new users within the system. Organizations should review their security configurations to ensure that roles are properly defined and that access controls are appropriately enforced. The fix demonstrates the importance of comprehensive security testing and configuration reviews, particularly for non-standard roles that may not be immediately obvious to administrators. This vulnerability highlights the need for adherence to security best practices and the implementation of proper role-based access controls that align with the principle of least privilege. The resolution also emphasizes the importance of maintaining consistent documentation of all security roles and their associated permissions to prevent unexpected access patterns.