CVE-2021-41644
📋 TL;DR
This vulnerability allows attackers to upload malicious PHP files disguised as images to the Online Food Ordering System, bypassing file upload filters. Successful exploitation enables remote code execution on the web server. Any organization using Sourcecodester Online Food Ordering System 2.0 is affected.
💻 Affected Systems
- Sourcecodester Online Food Ordering System
📦 What is this software?
Online Food Ordering System by Online Food Ordering System Project
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise allowing attackers to execute arbitrary commands, steal data, install backdoors, or pivot to internal networks.
Likely Case
Webshell deployment leading to data theft, defacement, or cryptocurrency mining malware installation.
If Mitigated
Limited impact with proper file upload restrictions and web application firewalls blocking malicious uploads.
🎯 Exploit Status
Exploit requires authentication to access upload functionality. Multiple public exploits exist demonstrating the bypass technique.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: Not available
Restart Required: No
Instructions:
No official patch exists. Consider upgrading to a newer version if available, or implement workarounds.
🔧 Temporary Workarounds
Restrict file upload extensions
allModify upload validation to strictly allow only image extensions (jpg, png, gif) and reject PHP files regardless of content.
Modify PHP upload validation code to check both file extension and MIME type
Web server file execution prevention
allConfigure web server to prevent execution of uploaded files in upload directories.
Apache: Add 'php_flag engine off' to .htaccess in upload directory
Nginx: location ~* \.php$ { deny all; } in upload directory
🧯 If You Can't Patch
- Disable file upload functionality completely if not essential
- Implement Web Application Firewall (WAF) rules to block PHP file uploads and suspicious POST requests
🔍 How to Verify
Check if Vulnerable:
Attempt to upload a PHP file with image extension (e.g., shell.php.jpg) through the system's upload interface.Check Version:
Check system documentation or admin panel for version informationVerify Fix Applied:
Test that PHP files cannot be uploaded regardless of extension, and uploaded files cannot be executed as PHP.📡 Detection & Monitoring
Log Indicators:
- File uploads with PHP content but image extensions
- POST requests to upload endpoints with suspicious filenames
- Web server errors from attempted PHP execution in upload directories
Network Indicators:
- HTTP POST requests with multipart/form-data containing PHP code
- Unusual outbound connections from web server after file upload
SIEM Query:
source="web_server" (method="POST" AND uri="*upload*" AND (filename="*.php*" OR content_type="application/x-php"))