CVE-2021-37389 in LMS
Summary
by MITRE • 08/11/2021
Chamilo 1.11.14 allows stored XSS via main/install/index.php and main/install/ajax.php through the port parameter.
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Analysis
by VulDB Data Team • 08/15/2021
The vulnerability CVE-2021-37389 represents a stored cross-site scripting flaw in the Chamilo learning management system version 1.11.14. This security weakness exists within the installation process of the platform, specifically in two key files: main/install/index.php and main/install/ajax.php. The vulnerability manifests through the improper handling of the port parameter, which allows attackers to inject malicious scripts that persist in the application's database and execute whenever the affected pages are accessed. This stored nature of the vulnerability makes it particularly dangerous as the malicious code remains active until manually removed from the system's database.
The technical implementation of this flaw stems from insufficient input validation and output sanitization within the installation routines of Chamilo. When users interact with the installation wizard and provide a port parameter, the system fails to properly sanitize this input before storing it in the database. The vulnerability follows CWE-79 - Improper Neutralization of Input During Web Page Generation, which specifically addresses the failure to properly escape or filter user-controllable data before it is rendered in web pages. The attack vector occurs during the installation phase when an attacker can manipulate the port parameter to inject malicious javascript code that gets stored and later executed in the context of other users' browsers.
The operational impact of this vulnerability extends beyond simple script execution as it can enable attackers to perform a wide range of malicious activities including session hijacking, credential theft, and data exfiltration. An attacker who successfully exploits this vulnerability can potentially escalate privileges, access sensitive user data, or even take control of the entire learning management system. The stored nature of the XSS attack means that any user who accesses the affected installation pages will be exposed to the malicious payload without requiring additional interaction from the victim. This makes the vulnerability particularly dangerous in multi-user environments where administrators and students all interact with the system. The attack follows patterns consistent with ATT&CK technique T1566.001 - Phishing: Spearphishing Attachment, as attackers can craft malicious installation pages that appear legitimate to unsuspecting administrators.
Mitigation strategies for CVE-2021-37389 should focus on immediate patching of the Chamilo platform to version 1.11.15 or later, which contains the necessary fixes for the input sanitization issues. Organizations should also implement additional defensive measures including input validation at multiple layers, output encoding for all dynamic content, and regular security scanning of installation directories. Network segmentation and access controls should be enforced to limit who can access installation pages, while web application firewalls can help detect and block suspicious port parameter values. Security monitoring should include database audit trails to detect unauthorized modifications to installation parameters, and regular security assessments should be conducted to ensure no other similar vulnerabilities exist within the system's installation routines. The remediation process must also include thorough testing to ensure that the patch does not introduce regressions in the installation functionality while maintaining the security improvements.