CVE-2013-4313 in Moodle
Summary
by MITRE
Moodle through 2.2.11, 2.3.x before 2.3.9, 2.4.x before 2.4.6, and 2.5.x before 2.5.2 does not prevent use of \0 characters in query strings, which might allow remote attackers to conduct SQL injection attacks against Microsoft SQL Server via a crafted string.
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Analysis
by VulDB Data Team • 05/12/2017
The vulnerability identified as CVE-2013-4313 represents a critical SQL injection weakness in Moodle learning management systems across multiple version ranges including 2.2.11 and earlier, 2.3.x versions before 2.3.9, 2.4.x versions before 2.4.6, and 2.5.x versions before 2.5.2. This flaw specifically targets the handling of null character sequences within query strings, creating an avenue for malicious actors to manipulate database interactions through carefully crafted input. The vulnerability stems from insufficient input validation and sanitization mechanisms that fail to properly escape or filter null characters, which are commonly used in SQL injection techniques to bypass security controls.
The technical exploitation of this vulnerability occurs when a remote attacker crafts malicious query strings containing null characters that are not properly handled by Moodle's database abstraction layer. Microsoft SQL Server, which is supported by Moodle, processes these null character sequences in ways that can be leveraged to inject malicious SQL commands into the database query execution flow. The null character, represented as in the vulnerability description, serves as a delimiter or termination character that can disrupt normal query parsing and potentially bypass standard SQL injection prevention measures. This weakness aligns with CWE-94, which categorizes improper control of generation of code, and specifically relates to CWE-89, SQL injection vulnerabilities where input validation fails to properly sanitize user-supplied data.
The operational impact of this vulnerability extends beyond simple data theft, as successful exploitation could enable attackers to execute arbitrary SQL commands against the Moodle database, potentially leading to complete system compromise. Attackers could leverage this weakness to extract sensitive user information, modify course content, manipulate user permissions, or even escalate privileges within the database. The vulnerability affects the core database interaction functionality of Moodle, making it particularly dangerous as it can be exploited through standard web interface interactions without requiring special privileges or access methods. Organizations using affected Moodle versions face significant risk of unauthorized data access and potential system compromise, especially in environments where Moodle serves as the primary educational platform.
Mitigation strategies for CVE-2013-4313 focus on immediate version upgrades to patched releases, with Moodle 2.3.9, 2.4.6, and 2.5.2 being the minimum recommended versions to address this vulnerability. Additionally, administrators should implement proper input validation at multiple layers including web application firewalls, database connection pooling configurations, and application-level sanitization routines. The ATT&CK framework categorizes this as a code injection technique under T1059, where adversaries leverage application vulnerabilities to execute malicious commands. Organizations should also consider implementing database activity monitoring, regular security assessments, and ensuring proper network segmentation to limit potential attack surface. The vulnerability demonstrates the importance of robust input validation and the need for security-conscious development practices that address all possible character sequences, including null characters, in user-supplied data handling mechanisms.