CVE-2013-1833 in Moodle
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in the File Picker module in 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 allow remote authenticated users to inject arbitrary web script or HTML via a crafted filename.
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Analysis
by VulDB Data Team • 01/01/2022
The CVE-2013-1833 vulnerability represents a critical cross-site scripting flaw within Moodle's File Picker module, affecting multiple versions of the popular learning management system. This vulnerability specifically targets the file upload and management functionality that allows users to browse and select files within the platform. The flaw exists in how the system processes and displays user-provided filenames, creating an opportunity for malicious actors to inject arbitrary web scripts or HTML content. The vulnerability impacts Moodle installations across several version branches including 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, indicating a widespread issue that affected a significant portion of the Moodle user base during that time period.
The technical exploitation of this vulnerability occurs when authenticated users with appropriate privileges upload or manipulate files with specially crafted filenames containing malicious script code. The File Picker module, which provides a graphical interface for selecting and managing files within Moodle, fails to properly sanitize or escape user input before rendering it in web pages. This lack of input validation and output sanitization creates a classic XSS attack vector where the malicious code executes in the context of other users' browsers who view the affected files. The vulnerability is particularly dangerous because it requires only authenticated access, meaning that users with legitimate accounts can exploit this flaw without requiring special privileges or external authentication.
From an operational standpoint, the impact of CVE-2013-1833 extends beyond simple script injection, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, and data exfiltration. The vulnerability allows attackers to execute scripts in the context of other users, potentially leading to complete compromise of user sessions and access to sensitive educational data. This risk is exacerbated by the fact that Moodle is widely used in educational institutions, making it an attractive target for attackers seeking to gain access to academic records, personal information, and institutional data. The attack surface is further expanded because the vulnerability affects the core file management functionality that is frequently used by both students and administrators, increasing the likelihood of successful exploitation.
Security professionals should consider this vulnerability in the context of the CWE (Common Weakness Enumeration) catalog, specifically mapping it to CWE-79 which represents "Cross-site Scripting" and CWE-20 which represents "Improper Input Validation." The vulnerability also aligns with ATT&CK techniques such as T1059.007 for "Command and Scripting Interpreter: JavaScript" and T1566 for "Phishing" as attackers could use the XSS capability to create malicious web pages that trick users into executing harmful code. Organizations should implement immediate mitigations including updating to patched versions of Moodle, implementing proper input validation and output encoding, and considering web application firewalls to detect and block malicious script payloads. Additionally, administrators should review user permissions and implement security awareness training to reduce the risk of successful exploitation through social engineering attacks that might leverage this vulnerability to compromise user sessions and data integrity.