CVE-2021-25003: WPCargo Track & Trace RCE Vulnerability

CVE-2021-25003 Overview

The WPCargo Track & Trace WordPress plugin before version 6.9.0 contains a critical vulnerability that allows unauthenticated attackers to write arbitrary PHP files anywhere on the web server. This vulnerability can lead to complete Remote Code Execution (RCE), enabling attackers to take full control of affected WordPress installations without requiring any authentication.

Critical Impact

Unauthenticated attackers can write malicious PHP files to arbitrary locations on the web server, leading to complete system compromise through Remote Code Execution.

Affected Products

• WPCargo Track & Trace WordPress plugin versions prior to 6.9.0
• WordPress installations using vulnerable WPCargo Track & Trace plugin versions
• Web servers hosting affected WordPress sites

Discovery Timeline

• 2022-03-14 - CVE-2021-25003 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-25003

Vulnerability Analysis

This vulnerability combines two dangerous weakness types: CWE-94 (Code Injection) and CWE-434 (Unrestricted Upload of File with Dangerous Type). The WPCargo Track & Trace plugin contains a file that fails to properly validate user input and authentication, allowing unauthenticated remote attackers to write PHP files to arbitrary locations on the web server.

The lack of authentication requirements means any remote attacker can exploit this vulnerability without needing valid credentials. Once a malicious PHP file is written to an accessible location on the server, the attacker can execute arbitrary code by simply requesting the uploaded file through the web server.

Root Cause

The root cause of this vulnerability is insufficient access control and input validation in the WPCargo Track & Trace plugin. The vulnerable component does not require authentication before processing file write operations, and fails to properly sanitize user-supplied file paths and content. This allows attackers to specify arbitrary file locations and inject malicious PHP code.

Attack Vector

The attack can be executed remotely over the network without requiring any user interaction or authentication. An attacker can exploit this vulnerability by sending specially crafted HTTP requests to the vulnerable endpoint. The attack workflow typically involves:

1. Identifying a WordPress site running a vulnerable version of WPCargo Track & Trace
2. Crafting a malicious request that specifies a PHP file path and malicious code content
3. Sending the request to write the malicious PHP file to an accessible web directory
4. Accessing the uploaded PHP file to execute arbitrary commands on the server

The vulnerability allows writing files to any location the web server process has write permissions for, which often includes the WordPress uploads directory, plugin directories, or theme directories.

Detection Methods for CVE-2021-25003

Indicators of Compromise

• Unexpected PHP files appearing in WordPress directories, particularly in /wp-content/uploads/, plugin folders, or theme directories
• Web server access logs showing suspicious POST requests to WPCargo Track & Trace plugin endpoints
• New PHP files with obfuscated code or web shell signatures
• Unusual outbound network connections from the web server process

Detection Strategies

• Monitor file system changes in WordPress directories for unexpected PHP file creation
• Implement Web Application Firewall (WAF) rules to detect and block malicious file upload attempts
• Review web server access logs for anomalous requests targeting WPCargo plugin endpoints
• Deploy integrity monitoring to detect unauthorized modifications to WordPress core, plugin, and theme files

Monitoring Recommendations

• Enable verbose logging for WordPress and monitor for file write operations from plugin code
• Set up alerts for new PHP file creation in WordPress directories
• Implement real-time file integrity monitoring for critical web server directories
• Monitor for unusual process execution originating from the web server process

How to Mitigate CVE-2021-25003

Immediate Actions Required

• Update WPCargo Track & Trace plugin to version 6.9.0 or later immediately
• If immediate updating is not possible, disable and remove the WPCargo Track & Trace plugin until patching is complete
• Conduct a thorough review of the WordPress installation for signs of compromise
• Check for unauthorized PHP files in all WordPress directories and remove any suspicious files
• Review web server access logs for evidence of exploitation attempts

Patch Information

The vulnerability has been addressed in WPCargo Track & Trace plugin version 6.9.0. Site administrators should update to this version or later through the WordPress plugin update mechanism or by downloading directly from the official WordPress plugin repository. For detailed vulnerability information, refer to the WPScan Vulnerability Advisory.

Workarounds

• Temporarily disable the WPCargo Track & Trace plugin if it cannot be immediately updated
• Implement WAF rules to block requests to vulnerable plugin endpoints
• Restrict write permissions on WordPress directories to prevent arbitrary file creation
• Use security plugins that can detect and block suspicious file upload attempts
• Consider network-level access controls to limit exposure of the WordPress administration interface

# Configuration example
# Restrict write permissions on WordPress directories
chmod -R 755 /var/www/html/wp-content/
chown -R www-data:www-data /var/www/html/wp-content/

# Block direct access to plugin files via .htaccess
# Add to wp-content/plugins/wpcargo-track-trace/.htaccess
<Files "*.php">
  Order Deny,Allow
  Deny from all
</Files>