CVE-2020-11546
📋 TL;DR
SuperWebMailer 7.21.0.01526 contains a critical remote code execution vulnerability in the Language parameter of mailingupgrade.php. Unauthenticated attackers can exploit this to execute arbitrary PHP code on affected systems. Any organization using this vulnerable version is at risk.
💻 Affected Systems
- SuperWebMailer
📦 What is this software?
Superwebmailer by Superwebmailer
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to install malware, steal data, pivot to other systems, or establish persistent backdoors.
Likely Case
Web server compromise leading to data theft, defacement, or use as part of a botnet.
If Mitigated
Attack blocked at network perimeter or detected before significant damage occurs.
🎯 Exploit Status
Simple HTTP request manipulation required. Public exploit code exists.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.22.0 or later
Vendor Advisory: https://www.superwebmailer.com/
Restart Required: No
Instructions:
1. Download latest version from vendor website. 2. Backup current installation. 3. Replace files with patched version. 4. Verify functionality.
🔧 Temporary Workarounds
Block access to mailingupgrade.php
allRestrict access to vulnerable file via web server configuration or firewall rules.
# Apache: RewriteRule ^mailingupgrade\.php$ - [F,L]
# Nginx: location ~ /mailingupgrade\.php$ { deny all; }
Input validation filter
allAdd input sanitization for Language parameter in PHP code.
// Add to mailingupgrade.php: $language = preg_replace('/[^a-zA-Z0-9_-]/', '', $_GET['Language']);
🧯 If You Can't Patch
- Isolate affected system in separate network segment with strict firewall rules.
- Implement web application firewall (WAF) with rules to block malicious Language parameter values.
🔍 How to Verify
Check if Vulnerable:
Check if /mailingupgrade.php exists and SuperWebMailer version is 7.21.0.01526.Check Version:
Check SuperWebMailer admin interface or readme files for version information.Verify Fix Applied:
Verify version is 7.22.0+ and test Language parameter with malicious payloads.📡 Detection & Monitoring
Log Indicators:
- HTTP requests to mailingupgrade.php with unusual Language parameter values
- PHP code execution errors in web server logs
Network Indicators:
- Unusual outbound connections from web server
- HTTP requests containing PHP code in parameters
SIEM Query:
source="web_server" AND uri="/mailingupgrade.php" AND (param="Language" AND value MATCHES "[^a-zA-Z0-9_-]")