CVE-2024-13521
📋 TL;DR
This CSRF vulnerability in the MailUp Auto Subscription WordPress plugin allows unauthenticated attackers to change plugin settings and inject malicious scripts by tricking administrators into clicking malicious links. All WordPress sites using this plugin up to version 1.1.0 are affected. The attack requires social engineering to get an administrator to perform an action while logged in.
💻 Affected Systems
- MailUp Auto Subscription WordPress Plugin
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could inject persistent malicious scripts into WordPress settings, leading to site defacement, credential theft via keyloggers, or malware distribution to visitors.
Likely Case
Attackers modify subscription settings to redirect users, collect email addresses maliciously, or inject ads/SEO spam into the site.
If Mitigated
With proper nonce validation and admin awareness, exploitation attempts fail, causing no impact beyond failed CSRF attempts.
🎯 Exploit Status
CSRF attacks are well-understood and easy to weaponize. No public exploit code needed - standard CSRF techniques work.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.2.0
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins → Installed Plugins. 3. Find 'MailUp Auto Subscription'. 4. Click 'Update Now' if available. 5. If no update appears, manually download version 1.2.0 from WordPress.org and replace plugin files.
🔧 Temporary Workarounds
Disable Plugin
allTemporarily deactivate the vulnerable plugin until patched
wp plugin deactivate mailup-auto-subscription
Add CSRF Protection Manually
allAdd nonce validation to the mas_options function in plugin code
Edit wp-content/plugins/mailup-auto-subscription/includes/class-mailup-auto-subscription.php and add wp_verify_nonce() checks
🧯 If You Can't Patch
- Implement strict Content Security Policy (CSP) headers to limit script injection impact
- Use WordPress security plugins that add CSRF protection globally
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin → Plugins → Installed Plugins → MailUp Auto Subscription → Version. If version is 1.1.0 or lower, you're vulnerable.Check Version:
wp plugin get mailup-auto-subscription --field=versionVerify Fix Applied:
After update, verify plugin version shows 1.2.0 or higher in WordPress admin panel.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /wp-admin/admin-post.php with action=mas_options
- Multiple failed CSRF attempts in WordPress security logs
- Unexpected changes to plugin settings without admin login records
Network Indicators:
- CSRF attack patterns: requests with Referer headers pointing to external domains
- Malicious iframe or script tags in plugin settings
SIEM Query:
source="wordpress" AND (uri_path="/wp-admin/admin-post.php" AND parameters.action="mas_options")