CVE-2021-24171 Explained : Impact and Mitigation

A detailed overview of the WooCommerce Upload Files plugin vulnerability that allowed unauthenticated arbitrary file upload.

Understanding CVE-2021-24171

This CVE describes a security vulnerability found in the WooCommerce Upload Files WordPress plugin before version 59.4 that could be exploited for unauthenticated arbitrary file upload.

What is CVE-2021-24171?

The WooCommerce Upload Files plugin, prior to version 59.4, had a single sanitization pass that could be bypassed to upload files with a PHP extension by manipulating certain parameters. Attackers could also perform a double extension attack and upload files to unauthorized locations using specific parameters.

The Impact of CVE-2021-24171

This vulnerability could allow attackers to upload malicious files to a server, potentially leading to unauthorized access, data breaches, or further exploitation of the affected system.

Technical Details of CVE-2021-24171

This section provides a deeper insight into the technical aspects of CVE-2021-24171.

Vulnerability Description

The vulnerability existed due to inadequate input validation in the plugin, enabling attackers to upload PHP files by manipulating parameters.

Affected Systems and Versions

The issue affected WooCommerce Upload Files plugin versions lower than 59.4, exposing websites using these versions to the risk of arbitrary file uploads.

Exploitation Mechanism

By embedding a 'blocked' extension within another 'blocked' extension in certain parameters, or using path traversal techniques, attackers could upload malicious files.

Mitigation and Prevention

To protect systems from CVE-2021-24171, immediate actions and long-term security practices are essential.

Immediate Steps to Take

Update the WooCommerce Upload Files plugin to version 59.4 or higher immediately.
Conduct a security audit to detect any unauthorized file uploads.

Long-Term Security Practices

Regularly monitor plugins for security updates and apply patches promptly.
Implement file upload restrictions and strong input validation mechanisms.

Patching and Updates

Stay informed about security advisories related to plugins and follow best practices for secure file uploads.