CVE-2020-5229 in Opencast
Summary
by MITRE
Opencast before 8.1 stores passwords using the rather outdated and cryptographically insecure MD5 hash algorithm. Furthermore, the hashes are salted using the username instead of a random salt, causing hashes for users with the same username and password to collide which is problematic especially for popular users like the default `admin` user. This essentially means that for an attacker, it might be feasible to reconstruct a user's password given access to these hashes. Note that attackers needing access to the hashes means that they must gain access to the database in which these are stored first to be able to start cracking the passwords. The problem is addressed in Opencast 8.1 which now uses the modern and much stronger bcrypt password hashing algorithm for storing passwords. Note, that old hashes remain MD5 until the password is updated. For a list of users whose password hashes are stored using MD5, take a look at the `/user-utils/users/md5.json` REST endpoint.
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Analysis
by VulDB Data Team • 03/27/2024
The vulnerability described in CVE-2020-5229 represents a critical cryptographic weakness in the Opencast media management system that has significant implications for user authentication security. This issue affects versions prior to 8.1 and stems from the implementation of outdated password storage mechanisms that violate fundamental security principles. The use of MD5 hashing algorithm for password storage creates a substantial risk vector since MD5 is widely recognized as cryptographically broken and unsuitable for password protection purposes. The vulnerability manifests through multiple interconnected flaws that compound the security risk, making it particularly dangerous for systems that rely on this software for content management and user access control.
The technical implementation flaw involves the improper application of salt values during the hashing process, which directly contravenes established security practices and creates predictable hash collisions. Specifically, the system employs username-based salting rather than random salt generation, a design choice that fundamentally undermines the security benefits of hashing. This approach creates a deterministic relationship between user credentials and their corresponding hash values, meaning that users sharing identical usernames and passwords will generate identical hash outputs. This vulnerability is particularly severe for high-privilege accounts such as the default admin user, where the collision effect becomes exponentially more problematic given the frequency of use and potential attack surface. The combination of weak hashing algorithm with predictable salting creates a situation where attackers can potentially reverse-engineer password values through various cracking techniques, especially when dealing with popular user accounts.
The operational impact of this vulnerability extends beyond simple credential compromise to encompass broader system security implications and potential unauthorized access scenarios. Attackers must first gain database access to obtain the MD5 hashes, which creates a multi-layered attack requirement but does not eliminate the risk entirely. Once hash access is achieved, the cryptographic weaknesses make password recovery significantly more feasible compared to systems using modern hashing algorithms. The vulnerability affects the entire user base of affected Opencast installations, with the most severe consequences for accounts that are frequently used or have elevated privileges. The persistence of MD5 hashes even after system upgrades until password changes occur creates a lingering security risk that extends the window of vulnerability beyond the initial discovery period. Organizations running vulnerable versions face potential unauthorized access to their media management systems, which could result in content manipulation, data exposure, or complete system compromise.
The remediation approach implemented in Opencast 8.1 demonstrates a proper security response through the adoption of modern cryptographic standards and practices. The transition from MD5 to bcrypt hashing represents a substantial improvement that aligns with industry best practices and established security frameworks. Bcrypt provides adaptive hashing with built-in salting mechanisms that make password recovery computationally expensive and practically infeasible through conventional means. This change addresses the core cryptographic weaknesses identified in the vulnerability while maintaining backward compatibility through the gradual migration of existing hashes. The inclusion of the `/user-utils/users/md5.json` REST endpoint provides administrators with visibility into affected accounts, enabling proactive security measures and risk assessment. This approach aligns with the principles outlined in CWE-327, which specifically addresses the use of weak cryptographic algorithms, and reflects the ATT&CK technique T1212 for exploiting credentials through hash cracking. The vulnerability serves as a clear example of how legacy security implementations can create persistent risks that require comprehensive remediation strategies rather than simple patching approaches.