CVE-2017-1000221 in Opencast
Summary
by MITRE
In Opencast 2.2.3 and older if user names overlap, the Opencast search service used for publication to the media modules and players will handle the access control incorrectly so that users only need to match part of the user name used for the access restriction. For example, a user with the role ROLE_USER will have access to recordings published only for ROLE_USER_X.
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Analysis
by VulDB Data Team • 12/08/2019
The vulnerability identified as CVE-2017-1000221 represents a critical access control flaw within the Opencast media management platform version 2.2.3 and earlier. This issue stems from improper handling of user name overlapping scenarios within the search service component that governs publication access controls for media modules and player interfaces. The vulnerability manifests when user names contain overlapping substrings, creating a scenario where access permissions are incorrectly evaluated. The core technical flaw resides in the search service's inability to properly distinguish between distinct user identifiers, leading to privilege escalation through partial name matching rather than exact user identification. This misconfiguration creates a scenario where users with specific access roles can bypass intended restrictions and gain unauthorized access to content designated for other users or roles.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it fundamentally compromises the integrity of the platform's access control mechanisms. When users with roles such as ROLE_USER attempt to access content restricted to ROLE_USER_X, they can successfully retrieve and view recordings that should remain inaccessible. This creates a significant security risk where sensitive media content can be accessed by users who only partially match the intended access criteria. The vulnerability affects the entire publication and distribution pipeline within Opencast, potentially exposing confidential recordings, educational materials, or proprietary content to unauthorized individuals. The flaw impacts both the media modules and player interfaces, creating a comprehensive access control failure across the platform's user-facing components.
This vulnerability aligns with CWE-285, which addresses improper authorization issues in software systems, and demonstrates characteristics consistent with privilege escalation attacks. The flaw can be categorized under ATT&CK technique T1078 which covers valid accounts and T1068 which involves exploit for privilege escalation. The root cause of this vulnerability lies in the search service's string matching algorithm, which fails to implement proper user identification protocols when dealing with overlapping user name patterns. Security researchers have identified that this issue represents a classic case of insufficient input validation and access control enforcement, where the system assumes that partial matching is sufficient for access determination rather than requiring complete user identification. The vulnerability essentially creates a backdoor where users can bypass access controls through simple name overlap rather than proper authentication and authorization mechanisms.
Organizations utilizing Opencast version 2.2.3 or earlier should immediately implement mitigations including upgrading to a patched version of the platform, implementing additional access control layers, and conducting comprehensive audits of user permissions and content access. The recommended approach involves ensuring that all user identifiers are properly validated and that access control decisions are based on complete user authentication rather than partial string matching. System administrators should also consider implementing monitoring solutions to detect unauthorized access attempts and review all content access logs for potential exploitation of this vulnerability. Additionally, organizations should conduct thorough security assessments of their media management systems to identify similar access control flaws that might exist in other components of their digital infrastructure.