CVE-2024-43440: Moodle's Local File Inclusion (LFI) Vulnerability in Block Backups Restoration Process

The popular Learning Management System (LMS), Moodle, has been affected by a crucial flaw, identified as CVE-2024-43440, which poses a significant security risk for both administrators and users of the platform. The vulnerability resides in a specific module that handles restoration of block backups. This flaw allows an attacker to exploit the local file inclusion (LFI) vulnerability resulting in potential risks and breaches when restoring block backups. This blog post aims to provide the details of the exploit, including code snippets, links to original references, and mitigation steps, in a simple and straightforward manner.

CVE-2024-43440: The Vulnerability

CVE-2024-43440 is classified as a Local File Inclusion (LFI) vulnerability that allows unauthorized users to read the contents of various sensitive files on the server, potentially leading to further attacks, such as data exfiltration or remote code execution. With this vulnerability, every instance of Moodle that allows restoration of block backups can be exploited to potentially compromise the security of the LMS. The flaw originates from improper handling of local file paths during backup restoration in the affected module, which could enable an attacker to manipulate the process and access unintended files.

The Exploit

The attacker can exploit the vulnerability by crafting a custom block backup file with malicious local file inclusion elements. By uploading this file and restoring backup through the affected functionality, the attacker can manipulate Moodle to include arbitrary local files and expose sensitive data, or potentially execute malicious code.

The following example demonstrates an attack vector that could exploit CVE-2024-43440

<?xml version="1." encoding="UTF-8"?>
<block version="2006100601">
    <component><![CDATA[../../../../../../etc/passwd]]></component>
</block>

In this XML file, the attacker uses the "../../../../../../etc/passwd" path to target the Linux system's password file to read its contents through the vulnerable module. When Moodle processes the malicious backup file, the system reads the Linux password file – exposing sensitive data.

The official CVE description and details can be found at the following link

- CVE-2024-43440 - NVD - US-Cert

The Moodle security advisory, providing a description and detailed information on the fix, can be accessed at:

- Moodle Security Advisory - MDL-xxxxx

Regularly update Moodle to ensure the latest security fixes are applied.

3. Implement strong access controls for backup restoration functionality, permitting only authorized users to restore backups.
4. Educate Moodle users and administrators about the risks, and provide guidelines for safely handling backups.

Closing Thoughts

While the CVE-2024-43440 flaw poses a significant risk for Moodle instances that allow restoration of block backups, properly addressing the issue through patching and adhering to best practices can ensure that your LMS stays protected. Administrators must remain diligent, and frequently update their Moodle instance to maintain a secure learning environment.

Timeline

Published on: 11/07/2024 14:15:16 UTC
Last modified on: 11/08/2024 19:01:03 UTC