CVE-2016-2190 in Moodle
Summary
by MITRE
Moodle through 2.6.11, 2.7.x before 2.7.13, 2.8.x before 2.8.11, 2.9.x before 2.9.5, and 3.0.x before 3.0.3 does not properly restrict links, which allows remote attackers to obtain sensitive URL information by reading a Referer log.
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Analysis
by VulDB Data Team • 08/21/2022
The vulnerability identified as CVE-2016-2190 affects Moodle learning management systems across multiple versions including 2.6.11 and earlier, 2.7.x versions before 2.7.13, 2.8.x versions before 2.8.11, 2.9.x versions before 2.9.5, and 3.0.x versions before 3.0.3. This issue stems from improper link restriction mechanisms within the platform that fail to adequately sanitize or validate URL references. The vulnerability is classified under CWE-611 as improper access control and aligns with ATT&CK technique T1071.004 for application layer protocol communication. The flaw specifically manifests when the system processes HTTP Referer headers without proper validation, allowing attackers to extract sensitive URL information from server logs.
The technical implementation of this vulnerability exploits the lack of proper input validation in Moodle's link handling mechanism. When users navigate through the platform, the system logs HTTP Referer headers which contain the URL of the previous page visited. In affected versions, these headers are not properly sanitized or restricted, enabling attackers to access potentially sensitive information contained within the referer URLs. This includes but is not limited to authentication tokens, session identifiers, or private resource paths that might reveal internal system structure or user-specific data. The vulnerability represents a significant information disclosure risk as it allows unauthorized access to data that should remain protected within the system's security boundaries.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks. Attackers can leverage the leaked URL information to construct targeted attacks against specific users or system components, particularly when the referer URLs contain session tokens or other authentication-related parameters. This weakness can be exploited in combination with other vulnerabilities to escalate privileges or gain unauthorized access to restricted resources within the Moodle environment. The vulnerability is particularly concerning in enterprise or academic settings where Moodle platforms may contain sensitive educational data, personal information, or confidential communication channels.
Organizations affected by this vulnerability should implement immediate mitigations including updating to the patched versions of Moodle as specified in the CVE details. The recommended approach involves applying the official security patches released by Moodle developers, which typically include enhanced input validation for Referer headers and improved link restriction mechanisms. Additional defensive measures include implementing proper web application firewall rules to filter suspicious Referer header content, configuring server-side logging to monitor for unusual URL patterns, and conducting regular security assessments to identify potential information leakage points within the application. Network administrators should also consider implementing monitoring solutions that can detect and alert on anomalous referer header patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and access control implementation in web applications, aligning with security best practices outlined in frameworks such as OWASP Top Ten and NIST Cybersecurity Framework.