CVE-2023-4220 : What You Need to Know

This CVE-2023-4220 advisory was published by STAR Labs on November 28, 2023. It involves an unrestricted file upload vulnerability in Chamilo LMS <= v1.11.24 that allows unauthenticated attackers to execute remote code through the uploading of a web shell.

Understanding CVE-2023-4220

The vulnerability identified as CVE-2023-4220 is a critical security issue in the Chamilo Learning Management System (LMS) version 1.11.24 and below. The flaw enables unauthenticated attackers to carry out stored cross-site scripting attacks and achieve remote code execution by exploiting the big file upload functionality within the system.

What is CVE-2023-4220?

The CVE-2023-4220 vulnerability allows malicious actors to upload a web shell through the unrestricted file upload feature in Chamilo LMS, leading to potential stored cross-site scripting attacks and unauthorized remote code execution. This poses a significant security risk to affected systems.

The Impact of CVE-2023-4220

The impact of CVE-2023-4220 is rated as high, with a CVSS base score of 8.1. The attack complexity is considered high, and it can result in severe consequences, including compromised confidentiality, integrity, and availability of the system. The vulnerability falls under CAPEC-650, which involves uploading a web shell to a web server.

Technical Details of CVE-2023-4220

This section delves into the specifics of the vulnerability, affected systems, and how the exploitation can be carried out.

Vulnerability Description

The vulnerability arises from the lack of proper restrictions in the big file upload functionality of Chamilo LMS version 1.11.24 and earlier. Attackers can abuse this flaw to upload a web shell, leading to stored cross-site scripting attacks and potential remote code execution within the system.

Affected Systems and Versions

Chamilo LMS versions up to and including 1.11.24 are confirmed to be impacted by CVE-2023-4220. Users and administrators of these versions are urged to take immediate action to mitigate the risk associated with this vulnerability.

Exploitation Mechanism

Unauthenticated attackers can exploit the unrestricted file upload feature in Chamilo LMS to upload a web shell through

/main/inc/lib/javascript/bigupload/inc/bigUpload.php

. This can enable them to execute remote code on the server and potentially compromise the entire system.

Mitigation and Prevention

Mitigating CVE-2023-4220 requires proactive steps to address the underlying security issue and prevent potential exploitation by malicious actors.

Immediate Steps to Take

Users of Chamilo LMS should upgrade to a patched version that addresses the unrestricted file upload vulnerability.
Implement proper input validation and access controls to limit file upload capabilities within the system.
Educate users about safe file upload practices and the risks associated with accepting files from untrusted sources.

Long-Term Security Practices

Regularly monitor for security advisories and updates related to Chamilo LMS to stay informed about potential vulnerabilities.
Conduct periodic security assessments and penetration testing to identify and remediate security weaknesses within the system.
Implement strong authentication mechanisms and access controls to protect sensitive functionalities from unauthorized access.

Patching and Updates

Users can mitigate the CVE-2023-4220 vulnerability by applying the patch provided by Chamilo LMS. The patch can be obtained from the official repository at the following URL: https://github.com/chamilo/chamilo-lms/commit/3b487a55076fb06f96809b790a35dcdd42f8ec49. It is essential to keep the system up to date with the latest security patches to ensure a secure environment.