CVE-2013-1835 in Moodle
Summary
by MITRE
Moodle 2.x through 2.1.10, 2.2.x before 2.2.8, 2.3.x before 2.3.5, and 2.4.x before 2.4.2 allows remote authenticated administrators to obtain sensitive information from the external repositories of arbitrary users by leveraging the login_as feature.
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Analysis
by VulDB Data Team • 01/01/2022
The vulnerability described in CVE-2013-1835 represents a critical information disclosure flaw within the Moodle learning management system that affects multiple version branches from 2.0 through 2.4. This security weakness specifically targets the login_as functionality which enables administrators to temporarily assume the identity of other users within the system. The vulnerability stems from insufficient access controls and validation mechanisms that fail to properly restrict administrative privileges when accessing external repository information. According to CWE-284, this issue manifests as an improper access control vulnerability where administrative users can bypass normal permission checks to access data they should not be authorized to view. The flaw exists in the way Moodle handles authentication contexts when administrators utilize the login_as feature, creating an unexpected pathway for privilege escalation and unauthorized data access.
The technical implementation of this vulnerability occurs through the manipulation of session contexts and user identity switching mechanisms within Moodle's core authentication system. When an administrator uses the login_as feature, the system should properly isolate the administrative session from the target user's data context, but this isolation fails to extend to external repository information. The flaw allows authenticated administrators to traverse user boundaries and access repository configurations, credentials, and other sensitive metadata that should remain protected within individual user contexts. This issue particularly affects external repository integrations such as those connecting to cloud storage services, database systems, or other external data sources that users have configured within their Moodle accounts. The vulnerability is classified under ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate administrative tools.
The operational impact of CVE-2013-1835 extends beyond simple information disclosure, as it provides attackers with potential access to sensitive user data and system configuration details that could facilitate further attacks. An attacker with administrative privileges could potentially extract external repository credentials, connection parameters, and user-specific access tokens that might allow them to access external systems beyond the Moodle platform. This vulnerability is particularly dangerous in educational environments where Moodle systems often integrate with external learning resources, institutional databases, and cloud-based storage solutions that contain sensitive student or institutional data. The exposure of repository information could enable attackers to conduct lateral movement attacks or gain access to other systems that rely on the same authentication mechanisms. Organizations using affected Moodle versions face significant risk of data breaches and compliance violations, particularly in environments governed by regulations such as FERPA or GDPR that mandate protection of educational and personal data.
Mitigation strategies for this vulnerability require immediate patching of affected Moodle installations to versions that address the access control flaw in the login_as feature. Administrators should implement strict role-based access controls and regularly audit administrative privileges to ensure that only necessary personnel have access to the login_as functionality. The system should enforce proper session isolation mechanisms that prevent administrative users from accessing user-specific data when operating under assumed identities. Organizations should also consider implementing additional monitoring controls to detect unauthorized use of administrative features and establish clear logging procedures for login_as activities. According to security best practices and industry standards, this vulnerability highlights the importance of principle of least privilege and proper access control implementation in web applications, particularly those handling sensitive educational data. The remediation process should include comprehensive testing to ensure that the patch does not introduce regressions in legitimate administrative functionality while maintaining the security controls necessary to prevent unauthorized access to user repository information.