CVE-2024-25925: Easy Checkout Field Editor File Upload Flaw

CVE-2024-25925 Overview

CVE-2024-25925 is an Unrestricted Upload of File with Dangerous Type vulnerability affecting the SYSBASICS WooCommerce Easy Checkout Field Editor, Fees & Discounts WordPress plugin. This vulnerability allows unauthenticated attackers to upload arbitrary files, including malicious PHP scripts, to vulnerable WordPress installations. The flaw exists in versions up to and including 3.5.12 of the plugin.

This vulnerability is particularly severe because it requires no authentication, meaning any remote attacker can exploit it to upload web shells or other malicious files, potentially leading to complete server compromise.

Critical Impact

Unauthenticated arbitrary file upload vulnerability allows remote attackers to execute malicious code on affected WordPress sites, potentially leading to full server takeover, data theft, and website defacement.

Affected Products

• SYSBASICS WooCommerce Easy Checkout Field Editor, Fees & Discounts versions up to and including 3.5.12
• WordPress installations running vulnerable versions of the phppoet-checkout-fields plugin
• E-commerce sites using affected WooCommerce checkout customization functionality

Discovery Timeline

• 2024-02-26 - CVE-2024-25925 published to NVD
• 2025-05-08 - Last updated in NVD database

Technical Details for CVE-2024-25925

Vulnerability Analysis

This vulnerability falls under CWE-434 (Unrestricted Upload of File with Dangerous Type), which occurs when an application allows users to upload files without properly validating or restricting the file types. In the context of the WooCommerce Easy Checkout Field Editor plugin, the file upload functionality lacks adequate security controls, enabling attackers to bypass intended restrictions.

The vulnerability is exploitable over the network without requiring any authentication or user interaction. Successful exploitation can result in complete compromise of confidentiality, integrity, and availability of the affected system. An attacker can upload PHP web shells to gain persistent remote access to the server.

Root Cause

The root cause of this vulnerability is the absence of proper file type validation in the plugin's upload handling mechanism. The plugin fails to:

1. Verify that uploaded files match expected file types (e.g., images only)
2. Check file contents against dangerous file signatures
3. Implement authentication requirements for file upload endpoints
4. Properly sanitize file names and extensions before storage

This oversight allows attackers to upload executable PHP files that can then be accessed directly via the web server to execute arbitrary commands.

Attack Vector

The attack vector involves sending specially crafted HTTP requests to the vulnerable file upload endpoint. Since the vulnerability is unauthenticated, attackers can target any WordPress site running the vulnerable plugin versions without requiring any credentials.

An attacker would typically:

1. Identify a WordPress site running the vulnerable plugin version
2. Craft a malicious PHP file (web shell) with a disguised or valid extension
3. Submit the malicious file to the vulnerable upload endpoint
4. Access the uploaded file via its web-accessible path
5. Execute arbitrary commands on the server through the web shell

The upload functionality in the WooCommerce Easy Checkout Field Editor plugin does not properly validate file types, allowing attackers to upload PHP files disguised as legitimate file types. The vulnerability exists because the plugin accepts file uploads without verifying that the file content matches the expected file type or restricting uploads to safe file extensions only. For detailed technical analysis, refer to the Patchstack Vulnerability Advisory.

Detection Methods for CVE-2024-25925

Indicators of Compromise

• Unexpected PHP files appearing in WordPress upload directories, particularly within plugin folders
• Unusual web shell signatures in uploaded files (e.g., eval(), base64_decode(), system(), exec() functions)
• Suspicious HTTP POST requests to checkout field upload endpoints from external IP addresses
• New files with executable extensions (.php, .phtml, .php5) in upload directories

Detection Strategies

• Monitor file system changes in WordPress upload directories and plugin folders for new executable files
• Implement web application firewall (WAF) rules to detect and block suspicious file upload attempts
• Enable file integrity monitoring (FIM) on WordPress installations to detect unauthorized file modifications
• Review web server access logs for POST requests to vulnerable plugin endpoints

Monitoring Recommendations

• Configure alerts for new file creations in the wp-content/uploads/ and plugin directories
• Monitor for outbound connections from the web server to unknown IP addresses
• Implement logging for all file upload operations with file hash verification
• Set up real-time alerting for detection of known web shell patterns in uploaded content

How to Mitigate CVE-2024-25925

Immediate Actions Required

• Update the WooCommerce Easy Checkout Field Editor plugin to the latest patched version immediately
• Audit WordPress upload directories for any suspicious or unexpected PHP files
• Review web server access logs for evidence of exploitation attempts
• Consider temporarily disabling the plugin until a patch can be applied if updates are not immediately available

Patch Information

Organizations should update the SYSBASICS WooCommerce Easy Checkout Field Editor, Fees & Discounts plugin to a version newer than 3.5.12. Check the plugin's official WordPress repository page or the vendor website for the latest secure version. The vulnerability was disclosed through Patchstack, and details are available in their vulnerability database.

Workarounds

• Implement server-side file upload restrictions to block PHP and other executable file types at the web server level
• Configure .htaccess rules to prevent PHP execution in upload directories
• Use a Web Application Firewall (WAF) to filter malicious file upload attempts
• Restrict access to plugin upload endpoints through IP whitelisting if file uploads are only needed internally

# Apache .htaccess configuration to prevent PHP execution in uploads directory
# Add to wp-content/uploads/.htaccess
<FilesMatch "\.(?:php[1-7]?|phtml|pht|phps)$">
    Require all denied
</FilesMatch>

# Alternative directive for older Apache versions
<Files *.php>
    deny from all
</Files>