CVE-2023-6901
📋 TL;DR
This is a critical OS command injection vulnerability in Stupid Simple CMS that allows remote attackers to execute arbitrary commands on the server. Attackers can exploit this by sending specially crafted HTTP POST requests to the /terminal/handle-command.php endpoint. All users running Stupid Simple CMS version 1.2.3 or earlier are affected.
💻 Affected Systems
- codelyfe Stupid Simple CMS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary commands as the web server user, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Attackers gain shell access to the server, allowing them to read sensitive files, modify website content, or use the server as a pivot point for further attacks.
If Mitigated
Attack is blocked at the network perimeter or web application firewall, preventing command execution but potentially revealing the vulnerability through failed attempts.
🎯 Exploit Status
Public proof-of-concept demonstrates exploitation with simple curl commands. The vulnerability requires no authentication and has straightforward exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: No
Instructions:
No official patch available. Consider upgrading to a newer version if available, or implement workarounds and consider alternative CMS solutions.
🔧 Temporary Workarounds
Block vulnerable endpoint
allRestrict access to /terminal/handle-command.php using web server configuration or firewall rules
# Apache: Add to .htaccess or virtual host config
<Files "handle-command.php">
Order deny,allow
Deny from all
</Files>
# Nginx: Add to server block
location ~ /terminal/handle-command\.php$ {
deny all;
return 403;
}
Input validation and sanitization
allImplement strict input validation for the 'command' parameter to only allow expected values
# Example PHP code to add to handle-command.php
$allowed_commands = ['ls', 'pwd', 'whoami'];
if (!in_array($_POST['command'], $allowed_commands)) {
die('Invalid command');
}
🧯 If You Can't Patch
- Implement a web application firewall (WAF) with command injection protection rules
- Network segmentation to isolate the CMS server from sensitive systems
🔍 How to Verify
Check if Vulnerable:
Test by sending a POST request to /terminal/handle-command.php with command parameter containing OS commands like 'whoami; id'Check Version:
Check CMS version in admin panel or look for version files in installation directoryVerify Fix Applied:
Attempt the same exploit after implementing workarounds - should receive 403 error or validation failure📡 Detection & Monitoring
Log Indicators:
- POST requests to /terminal/handle-command.php containing shell metacharacters (;, |, &, $)
- Unusual command execution in web server logs
- Multiple failed attempts to access the vulnerable endpoint
Network Indicators:
- HTTP POST requests to /terminal/handle-command.php with command parameter containing shell commands
- Unusual outbound connections from web server to command and control servers
SIEM Query:
source="web_server" AND (url="/terminal/handle-command.php" OR command="*;*" OR command="*|*" OR command="*&*")