CVE-2012-5479 in Moodle
Summary
by MITRE
The Portfolio plugin in Moodle 2.1.x before 2.1.9, 2.2.x before 2.2.6, and 2.3.x before 2.3.3 allows remote authenticated users to upload and execute files via a modified Portfolio API callback.
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Analysis
by VulDB Data Team • 02/24/2019
The vulnerability identified as CVE-2012-5479 represents a critical security flaw in the Moodle learning management system's Portfolio plugin, affecting versions prior to the specified patches. This issue stems from inadequate input validation and sanitization within the Portfolio API callback mechanism, creating a pathway for authenticated attackers to escalate their privileges and execute arbitrary code on affected systems. The vulnerability specifically targets the file upload functionality that is part of Moodle's portfolio export capabilities, which are designed to allow users to export course content to external services or platforms. The flaw exists because the system fails to properly validate the callback parameters received from external portfolio services, allowing malicious actors to manipulate these parameters to trigger unintended file upload operations.
The technical exploitation of this vulnerability requires an authenticated user account within the Moodle system, which significantly reduces the attack surface compared to fully unauthenticated exploits. However, the impact remains severe as it allows attackers to upload malicious files to the server and subsequently execute them with the privileges of the web server process. This typically results in remote code execution capabilities that can be leveraged to establish persistent access, escalate privileges, or compromise the entire Moodle installation. The vulnerability manifests through a modified Portfolio API callback where the attacker can inject malicious file paths or content into the callback parameters, bypassing normal file upload restrictions. This flaw aligns with CWE-434, which describes insecure file upload vulnerabilities where applications accept files from untrusted sources without proper validation. The attack vector is particularly concerning because it operates within the legitimate functionality of the system, making it harder to detect through standard security monitoring.
From an operational perspective, the exploitation of this vulnerability can lead to complete compromise of the Moodle platform and potentially the underlying server infrastructure. Attackers can upload web shells or other malicious payloads that provide them with persistent access to the system, enabling data exfiltration, modification of course content, or use of the platform as a launchpad for further attacks within the organization's network. The affected versions of Moodle were widely used in educational institutions, making this vulnerability particularly dangerous as it could impact thousands of academic environments. The vulnerability also demonstrates poor input validation practices in the Portfolio plugin's API implementation, where the system trusted external callbacks without proper sanitization or verification. This type of vulnerability is categorized under the ATT&CK framework as T1059.007 - Command and Scripting Interpreter: PowerShell, though the actual exploitation occurs through web-based file upload mechanisms rather than PowerShell specifically. Organizations using affected Moodle versions face significant risk of data breaches, service disruption, and potential compliance violations, especially in environments where student data is handled.
The recommended mitigation strategies for CVE-2012-5479 involve immediate patching of all affected Moodle installations to the patched versions mentioned in the advisory. System administrators should also implement network-level restrictions to limit access to the Portfolio plugin functionality, particularly when it is not actively needed. Additional security measures include implementing strict file upload validation, monitoring for unusual file upload activities, and conducting regular security audits of the Moodle installation. Organizations should also consider implementing web application firewalls to detect and block malicious callback parameters. The vulnerability underscores the importance of proper input validation and the principle of least privilege in web application security, where even authenticated users should not be granted unrestricted access to critical system functions. Regular security updates and vulnerability assessments are essential to maintaining the security posture of learning management systems, particularly those handling sensitive educational data. This vulnerability serves as a reminder of the critical need for secure coding practices and thorough testing of all external API integrations within web applications.