CVE-2023-1405
📋 TL;DR
This vulnerability in the Formidable Forms WordPress plugin allows anonymous attackers to perform PHP Object Injection by exploiting insecure deserialization of user input. This affects WordPress sites running vulnerable versions of the plugin, potentially leading to remote code execution or other malicious activities.
💻 Affected Systems
- Formidable Forms WordPress Plugin
📦 What is this software?
Formidable Forms by Strategy11
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete site compromise, data theft, or server takeover.
Likely Case
Arbitrary code execution within the WordPress context, potentially creating backdoors, modifying content, or stealing sensitive data.
If Mitigated
Limited impact if proper input validation and security controls prevent exploitation attempts.
🎯 Exploit Status
Exploitation requires a suitable gadget chain in PHP classes, but such chains are commonly available in WordPress environments.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.2 and later
Vendor Advisory: https://wpscan.com/vulnerability/8c727a31-ff65-4472-8191-b1becc08192a/
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins > Installed Plugins. 3. Find Formidable Forms and click 'Update Now'. 4. Verify the plugin version is 6.2 or higher.
🔧 Temporary Workarounds
Disable Formidable Forms Plugin
allTemporarily disable the vulnerable plugin until patching is possible.
wp plugin deactivate formidable
Web Application Firewall Rule
allBlock requests containing serialized PHP object patterns.
🧯 If You Can't Patch
- Implement strict input validation to reject serialized data in user inputs.
- Use a web application firewall (WAF) with rules to detect and block PHP object injection attempts.
🔍 How to Verify
Check if Vulnerable:
Check the plugin version in WordPress admin under Plugins > Installed Plugins. If version is below 6.2, the site is vulnerable.Check Version:
wp plugin get formidable --field=versionVerify Fix Applied:
Confirm the plugin version is 6.2 or higher in the WordPress admin panel.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to Formidable Forms endpoints
- PHP errors related to unserialize() or object injection
Network Indicators:
- HTTP requests containing serialized PHP object patterns (e.g., O:8:"stdClass")
SIEM Query:
source="web_logs" AND (uri_path="/wp-admin/admin-ajax.php" OR uri_path CONTAINS "formidable") AND http_method="POST" AND (request_body CONTAINS "O:" OR request_body CONTAINS "a:")