CVE-2024-27957: Pie Register Path Traversal Vulnerability

CVE-2024-27957 Overview

CVE-2024-27957 is an Unrestricted Upload of File with Dangerous Type vulnerability affecting the Pie Register plugin for WordPress. This critical security flaw allows unauthenticated attackers to upload arbitrary files with dangerous types to the vulnerable web server, potentially leading to remote code execution and complete site compromise.

Critical Impact

Unauthenticated attackers can exploit this vulnerability to upload malicious files such as PHP web shells, enabling complete takeover of affected WordPress installations without requiring any authentication.

Affected Products

• Genetechsolutions Pie Register versions from n/a through 3.8.3.1
• WordPress installations running vulnerable versions of Pie Register plugin

Discovery Timeline

• 2024-03-17 - CVE-2024-27957 published to NVD
• 2025-02-27 - Last updated in NVD database

Technical Details for CVE-2024-27957

Vulnerability Analysis

This vulnerability falls under CWE-434 (Unrestricted Upload of File with Dangerous Type), a severe class of web application vulnerabilities. The Pie Register plugin fails to properly validate and restrict file types during the upload process, allowing attackers to bypass intended security controls.

The vulnerability is exploitable over the network without requiring any authentication or user interaction. An attacker can leverage this flaw to upload executable files such as PHP scripts to the WordPress server. Once uploaded, these malicious files can be accessed directly through the web server, enabling arbitrary code execution in the context of the web application.

Root Cause

The root cause of CVE-2024-27957 lies in insufficient file type validation within the Pie Register plugin's upload handling functionality. The plugin fails to implement proper server-side validation of uploaded file extensions and MIME types, relying potentially only on client-side controls that can be trivially bypassed by attackers.

Proper mitigation would require implementing a whitelist of allowed file extensions, validating MIME types on the server side, storing uploads outside the web root, and randomizing uploaded file names to prevent direct execution.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no authentication (unauthenticated) and no user interaction. An attacker can craft a malicious HTTP request containing a file with a dangerous type (such as a PHP web shell) and submit it to the vulnerable file upload endpoint exposed by the Pie Register plugin.

The exploitation process typically involves:

1. Identifying a WordPress site running a vulnerable version of Pie Register
2. Crafting a malicious file (e.g., PHP web shell) with appropriate headers
3. Sending a multipart form request to the vulnerable upload endpoint
4. Accessing the uploaded malicious file directly via the web server
5. Executing arbitrary commands on the compromised server

Technical details about this vulnerability can be found in the Patchstack WordPress Vulnerability Alert.

Detection Methods for CVE-2024-27957

Indicators of Compromise

• Unexpected PHP files or web shells in WordPress upload directories, particularly in /wp-content/uploads/ or Pie Register-related directories
• Unusual HTTP POST requests to Pie Register plugin endpoints with file upload payloads
• Newly created files with suspicious names or obfuscated PHP code in plugin directories
• Web server logs showing requests to unfamiliar PHP files in upload paths

Detection Strategies

• Implement file integrity monitoring (FIM) on WordPress directories to detect unauthorized file additions
• Configure web application firewall (WAF) rules to block requests containing potentially malicious file uploads
• Monitor HTTP POST requests to the Pie Register plugin for suspicious file types and content
• Deploy endpoint detection and response (EDR) solutions to identify malicious script execution on web servers

Monitoring Recommendations

• Enable comprehensive logging for all file upload activities within WordPress
• Set up alerts for new executable files created in web-accessible directories
• Monitor for outbound connections from the web server that could indicate a compromised shell
• Review access logs for patterns consistent with web shell reconnaissance and exploitation

How to Mitigate CVE-2024-27957

Immediate Actions Required

• Update the Pie Register plugin to a version newer than 3.8.3.1 immediately
• Audit WordPress upload directories for any suspicious or unexpected files
• If updating is not immediately possible, consider temporarily disabling the Pie Register plugin
• Review web server access logs for signs of exploitation attempts

Patch Information

Organizations running Genetechsolutions Pie Register should update to the latest patched version that addresses this arbitrary file upload vulnerability. The vulnerability affects all versions through 3.8.3.1. Administrators should check the WordPress plugin repository or the vendor's official site for the latest secure release.

For detailed vulnerability information, refer to the Patchstack advisory.

Workarounds

• Disable the Pie Register plugin until a patch can be applied
• Implement web application firewall (WAF) rules to block suspicious file upload requests targeting the plugin
• Restrict file upload permissions at the server level to prevent execution of uploaded PHP files
• Configure .htaccess rules to deny direct access to upload directories

# Example .htaccess configuration to prevent PHP execution in uploads directory
# Place this file in wp-content/uploads/
<FilesMatch "\.php$">
    Order Allow,Deny
    Deny from all
</FilesMatch>

# Alternative for Apache 2.4+
<FilesMatch "\.php$">
    Require all denied
</FilesMatch>