CVE-2014-3542 in Moodle
Summary
by MITRE
mod/lti/service.php in Moodle through 2.3.11, 2.4.x before 2.4.11, 2.5.x before 2.5.7, 2.6.x before 2.6.4, and 2.7.x before 2.7.1 allows remote attackers to read arbitrary files via an XML external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
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Analysis
by VulDB Data Team • 06/04/2017
The vulnerability described in CVE-2014-3542 represents a critical XML External Entity (XXE) flaw within Moodle's LTI service component that affects multiple versions of the popular learning management system. This vulnerability exists in the mod/lti/service.php file and enables remote attackers to perform unauthorized file access operations through carefully crafted XML requests that exploit XXE mechanisms. The flaw specifically manifests when the application processes XML data containing external entity declarations that reference local files on the server, allowing attackers to read arbitrary files from the system filesystem.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within Moodle's LTI service handler. When the system processes XML requests containing external entity references, it fails to properly restrict or disable external entity resolution, creating a pathway for attackers to specify arbitrary file paths that can be resolved and returned in the application's response. This particular XXE implementation allows for file disclosure attacks where attackers can access sensitive files such as configuration files, database credentials, or system files that should remain protected from unauthorized access.
From an operational perspective, this vulnerability poses significant risks to organizations using affected Moodle versions, as it can lead to complete system compromise through information disclosure. Attackers can leverage this flaw to extract sensitive data including database connection strings, user credentials, application configuration files, and potentially system-level information that could facilitate further exploitation. The impact extends beyond simple data theft since the ability to read arbitrary files can expose system internals that may reveal additional vulnerabilities or provide attackers with the information needed to escalate privileges or conduct more sophisticated attacks.
The vulnerability aligns with CWE-611 (Improper Restriction of XML External Entity Reference) and follows patterns commonly associated with XXE attacks documented in the ATT&CK framework under techniques such as T1566 (Phishing with Malicious Attachments) and T1071.3 (Application Layer Protocol: Web Protocols). Organizations should immediately implement mitigations including disabling external entity resolution in XML parsers, implementing proper input validation for all XML processing components, and restricting file access permissions for the web application. Additionally, network-level controls such as web application firewalls can help detect and block malicious XXE payloads, while regular security updates and patch management processes should be enforced to prevent exploitation of known vulnerabilities in the LTI service component.