Drupal H5P Module <= 2.0.0 (isValidPackage) Zip Slip Vulnerability


• Affected Versions:

Version 2.0.0-alpha2 and prior versions.

Version 7.x-1.50 and prior versions.

• Vulnerability Description:

The vulnerability is located within the H5PValidator::isValidPackage() method. This implements the following check in order to skip any file or folder starting with a dot or underscore within the uploaded h5p archive:

891$fileName = $zip->statIndex($i)['name'];
893if (preg_match('/(^[\._]|\/[\._])/', $fileName) !== 0) {
894  continue; // Skip any file or folder starting with a . or _

This regex check should be enough to prevent path traversal attacks through zipped filenames (Zip Slip attacks), because it checks for the string “/.” within the filename, thus preventing directory traversal attacks. However, the vulnerability exists if Drupal is running on a Windows server, because in this case the attacker can provide a malicious h5p archive containing a filename with path traversal sequences like “..\..\..”, which would bypass the above regex check. This can be exploited to write (or overwrite) semi-arbitrary files in the file system via directory traversal sequences, potentially leading to Stored Cross-Site Scripting (XSS) and other kind of attacks.

• Solution:

Upgrade to version 7.x-1.51, 2.0.0-alpha3, or later.

• Disclosure Timeline:

[22/11/2021] – Vendor notified

[28/02/2022] – Vendor proposed a possible patch

[28/02/2022] – Vendor notified about the ineffective patch, provided a fix suggestion

[01/03/2022] – Vendor fixed the previous patch

[30/03/2022] – Asked update about the public disclosure and release of a patch, no response

[22/11/2022] – After one year still no official solution available

[03/12/2022] – Public disclosure

[14/12/2022] – Vendor update released

• CVE Reference:

The Common Vulnerabilities and Exposures project (cve.mitre.org) has not assigned a CVE identifier for this vulnerability.

• Credits:

Vulnerability discovered by Egidio Romano.

• Other References: