CVE-2021-24565
📋 TL;DR
This vulnerability in the Contact Form 7 Captcha WordPress plugin allows attackers to change plugin settings without user consent via CSRF attacks, and inject malicious scripts that persist on the site. It affects WordPress sites using vulnerable versions of this plugin, particularly those with administrative users who can manage plugin settings.
💻 Affected Systems
- Contact Form 7 Captcha WordPress Plugin
📦 What is this software?
Contact Form 7 Captcha by Contact Form 7 Captcha Project
⚠️ Risk & Real-World Impact
Worst Case
Attackers could inject persistent malicious scripts that steal admin credentials, redirect users to malicious sites, or deface the website, potentially leading to complete site compromise.
Likely Case
Attackers trick administrators into clicking malicious links that change plugin settings or inject basic XSS payloads, potentially stealing session cookies or performing unauthorized actions.
If Mitigated
With proper CSRF protections and input validation, the attack would fail, preventing unauthorized setting changes and script injection.
🎯 Exploit Status
Exploitation requires tricking an authenticated admin user to click a malicious link or visit a crafted page. The CSRF and XSS vulnerabilities are straightforward to exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.0.9 and later
Vendor Advisory: https://plugins.trac.wordpress.org/changeset/2570402
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins > Installed Plugins. 3. Find 'Contact Form 7 Captcha' and update to version 0.0.9 or later. 4. If auto-update is available, click 'Update Now'.
🔧 Temporary Workarounds
Disable vulnerable plugin
allTemporarily disable the Contact Form 7 Captcha plugin until patched
wp plugin deactivate contact-form-7-captcha
Implement CSRF protection manually
allAdd nonce verification to plugin settings page via custom code
🧯 If You Can't Patch
- Restrict admin access to trusted networks only
- Implement web application firewall rules to block XSS payloads
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin panel > Plugins > Installed Plugins for Contact Form 7 Captcha version. If version is below 0.0.9, you are vulnerable.Check Version:
wp plugin get contact-form-7-captcha --field=versionVerify Fix Applied:
After updating, verify the plugin version shows 0.0.9 or higher in WordPress admin.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to wp-admin/admin.php?page=cf7-captcha
- Multiple failed CSRF token validations
- Suspicious script tags in plugin settings
Network Indicators:
- HTTP requests with malicious script payloads in parameters
- CSRF attack patterns targeting admin endpoints
SIEM Query:
source="wordpress.log" AND ("cf7-captcha" OR "admin.php?page=cf7-captcha") AND (status=200 OR status=302)