CVE-2020-5230 in Opencast
Summary
by MITRE
Opencast before 8.1 and 7.6 allows almost arbitrary identifiers for media packages and elements to be used. This can be problematic for operation and security since such identifiers are sometimes used for file system operations which may lead to an attacker being able to escape working directories and write files to other locations. In addition, Opencast's Id.toString(?) vs Id.compact(?) behavior, the latter trying to mitigate some of the file system problems, can cause errors due to identifier mismatch since an identifier may unintentionally change. This issue is fixed in Opencast 7.6 and 8.1.
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Analysis
by VulDB Data Team • 03/27/2024
The vulnerability identified as CVE-2020-5230 represents a critical security flaw in Opencast media management systems prior to versions 7.6 and 8.1, where the software fails to properly validate identifiers used for media packages and elements. This weakness stems from insufficient input sanitization mechanisms that allow attackers to submit arbitrary identifiers which are subsequently processed in file system operations. The vulnerability exposes the system to potential directory traversal attacks and unauthorized file system modifications, as the software does not adequately restrict the characters or formats that can be used in identifier fields. The issue particularly affects systems where identifiers are directly used in file path constructions, creating opportunities for attackers to escape designated working directories and gain access to unintended file system locations. This represents a fundamental failure in secure input validation practices that violates established security principles for preventing path traversal vulnerabilities.
The technical implementation of this vulnerability manifests through Opencast's handling of identifier formatting methods, specifically the inconsistent behavior between Id.toString() and Id.compact() functions. The Id.compact() method was introduced as a mitigation strategy to address some file system security concerns by normalizing identifier formats, however this approach introduces its own complications. The mismatch between these two identifier representations creates a scenario where identifiers may be processed differently depending on the context in which they are used, leading to operational errors and potential security bypasses. This design flaw creates a race condition where the same identifier can be interpreted differently by various system components, resulting in unpredictable behavior and potential privilege escalation opportunities. The vulnerability is categorized under CWE-22 Path Traversal and CWE-770 Allocation of Resources Without Limits or Throttling, which are fundamental security weaknesses that directly impact system integrity and access controls. The inconsistent identifier handling also creates challenges for system administrators and developers who must account for these behavioral differences in their operational procedures.
The operational impact of CVE-2020-5230 extends beyond simple file system manipulation to encompass broader system compromise scenarios that can affect media processing workflows and data integrity. Attackers can exploit this vulnerability to write files to arbitrary locations on the file system, potentially leading to unauthorized data modification, information disclosure, or even system takeover through malicious file placement. The vulnerability is particularly concerning in multi-tenant environments where different users or processes may be operating under different security contexts, as it could enable cross-tenant data access or modification. The identifier mismatch issues also create operational instability, as system errors may occur when components expect one identifier format but receive another, potentially causing service disruptions or data corruption. This vulnerability directly impacts the principle of least privilege and can be leveraged to escalate privileges within the system, making it a significant concern for organizations relying on Opencast for media processing and distribution. The issue aligns with ATT&CK technique T1059 Command and Scripting Interpreter, where attackers may use the compromised identifier handling to execute malicious commands through file system manipulation.
Mitigation strategies for CVE-2020-5230 require immediate implementation of version upgrades to Opencast 7.6 or 8.1, which contain the necessary fixes for identifier validation and processing. Organizations should conduct comprehensive security assessments to identify any existing compromised identifiers that may have been used in the system prior to patching. System administrators should implement additional monitoring for unusual file system access patterns and identifier usage that could indicate exploitation attempts. The fix addresses the core issue by implementing proper identifier validation that prevents problematic characters from being accepted in media package identifiers, while also ensuring consistent behavior between the toString() and compact() methods. Additional defensive measures include implementing proper input sanitization at multiple layers of the application, configuring restrictive file system permissions, and establishing automated monitoring for directory traversal attempts. Organizations should also review their existing media processing workflows to ensure that identifier handling does not introduce additional attack vectors and consider implementing additional validation checks for all identifier inputs. The solution addresses the underlying architectural flaw by establishing consistent identifier processing behavior and preventing the escape of file system operations that could lead to unauthorized access.