CVE-2020-5206 in Opencast
Summary
by MITRE
In Opencast before 7.6 and 8.1, using a remember-me cookie with an arbitrary username can cause Opencast to assume proper authentication for that user even if the remember-me cookie was incorrect given that the attacked endpoint also allows anonymous access. This way, an attacker can, for example, fake a remember-me token, assume the identity of the global system administrator and request non-public content from the search service without ever providing any proper authentication. This problem is fixed in Opencast 7.6 and Opencast 8.1
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Analysis
by VulDB Data Team • 03/27/2024
The vulnerability described in CVE-2020-5206 represents a critical authentication bypass flaw in Opencast media management systems prior to versions 7.6 and 8.1. This issue stems from improper handling of remember-me cookies within the authentication mechanism, creating a pathway for unauthorized access to protected system resources. The vulnerability specifically manifests when the system processes remember-me tokens without adequately validating their authenticity against the actual user credentials, particularly in scenarios where endpoints permit anonymous access.
The technical flaw resides in the authentication flow where the system accepts remember-me cookies as valid authentication tokens regardless of whether they correspond to legitimate user sessions or have been tampered with. This behavior creates a condition where an attacker can generate or manipulate a remember-me cookie containing an arbitrary username, specifically targeting the global system administrator account. The vulnerability exploits the system's assumption that any remember-me cookie, even one with incorrect or forged content, should grant access to protected resources when the endpoint also supports anonymous access modes. This design flaw allows attackers to bypass standard authentication checks entirely.
The operational impact of this vulnerability is severe as it enables attackers to assume administrative privileges without providing valid credentials. An attacker can fake a remember-me token and gain access to the global system administrator identity, which typically has unrestricted access to all system functions and protected content. This includes the ability to retrieve non-public content from the search service and potentially access sensitive system configurations or media assets. The vulnerability essentially allows for privilege escalation and unauthorized data access, making it particularly dangerous in environments where Opencast systems manage confidential or copyrighted media content.
This vulnerability aligns with CWE-287, which addresses improper authentication issues in software systems, and relates to ATT&CK technique T1078.004 for valid accounts and T1566 for credential harvesting. The flaw demonstrates poor input validation and authentication token handling practices that violate fundamental security principles. Organizations using affected Opencast versions face significant risk of unauthorized access to their media management systems, potentially leading to data breaches, content theft, or system compromise. The fix implemented in Opencast 7.6 and 8.1 addresses the core authentication bypass by enforcing proper validation of remember-me tokens against legitimate user sessions and ensuring that anonymous access endpoints do not inadvertently permit unauthorized privilege escalation. Organizations should immediately upgrade to the patched versions and review their authentication configurations to prevent exploitation of this vulnerability.