CVE-2023-4220 in LMS
Summary
by MITRE • 11/28/2023
Unrestricted file upload in big file upload functionality in `/main/inc/lib/javascript/bigupload/inc/bigUpload.php` in Chamilo LMS <= v1.11.24 allows unauthenticated attackers to perform stored cross-site scripting attacks and obtain remote code execution via uploading of web shell.
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Analysis
by VulDB Data Team • 03/21/2025
The vulnerability identified as CVE-2023-4220 represents a critical security flaw in the Chamilo Learning Management System version 1.11.24 and earlier. This issue resides within the big file upload functionality located in the file path `/main/inc/lib/javascript/bigupload/inc/bigUpload.php`. The vulnerability stems from inadequate input validation and sanitization mechanisms that permit unrestricted file uploads, creating a pathway for malicious actors to bypass authentication requirements and inject dangerous payloads into the system.
The technical implementation of this vulnerability involves a lack of proper file type checking and content validation during the upload process. Attackers can exploit this weakness by uploading malicious files that contain web shells or malicious javascript code. The absence of file extension filtering, MIME type validation, and content analysis allows attackers to upload files with dangerous extensions such as .php, .jsp, or .asp that can execute code on the server. This flaw directly maps to CWE-434 which describes the weakness of unrestricted upload of file with dangerous type, and aligns with ATT&CK technique T1190 which covers exploiting vulnerabilities in web applications.
The operational impact of this vulnerability is severe and multifaceted. Once an attacker successfully uploads a malicious file, they can achieve stored cross-site scripting attacks that persist in the system and affect multiple users who access the vulnerable functionality. More critically, the vulnerability enables remote code execution capabilities that allow attackers to gain full control over the affected server. This includes the ability to execute arbitrary commands, access sensitive data, modify system files, and potentially establish persistent backdoors. The unauthenticated nature of the attack means that any user can exploit this vulnerability without requiring valid credentials, making it particularly dangerous for publicly accessible systems.
Organizations using Chamilo LMS versions up to 1.11.24 face significant risk exposure with this vulnerability. The implications extend beyond immediate system compromise to include potential data breaches, service disruption, and regulatory compliance violations. The vulnerability's location within core file upload functionality means that it affects the platform's fundamental security posture and could be leveraged as a foothold for further attacks within the network infrastructure. The attack surface is particularly concerning given that LMS platforms typically store sensitive educational data, user information, and institutional content that could be compromised through this vulnerability.
The recommended mitigation strategy involves immediate patching of the Chamilo LMS platform to version 1.11.25 or later where this vulnerability has been addressed. Organizations should implement comprehensive file upload restrictions including strict MIME type validation, file extension filtering, and content analysis to prevent execution of malicious code. Additional security measures should include restricting upload permissions, implementing proper file access controls, and conducting regular security audits of upload functionality. Network segmentation and monitoring should be enhanced to detect and prevent unauthorized file uploads, while implementing web application firewalls can provide additional protection layers. The remediation process should also include comprehensive security training for administrators and regular vulnerability assessments to prevent similar issues in other components of the system.