CVE-2020-23828
📋 TL;DR
CVE-2020-23828 is a critical file upload vulnerability in SourceCodester Online Course Registration v1.0 that allows remote attackers to upload malicious PHP files disguised as images, leading to remote code execution on the web server. This affects any organization using this specific software version without proper file upload validation.
💻 Affected Systems
- SourceCodester Online Course Registration
📦 What is this software?
Online Course Registration by Online Course Registration Project
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the web server with attacker gaining full control, data theft, lateral movement to internal networks, and deployment of persistent backdoors.
Likely Case
Attackers upload web shells to execute arbitrary commands, deface websites, steal sensitive data, or use the server for further attacks.
If Mitigated
If proper file upload controls and web application firewalls are in place, exploitation attempts are blocked and logged.
🎯 Exploit Status
Exploit requires authentication to access my-profile.php, but the file upload bypass is straightforward. Public exploit code is available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: Not available
Restart Required: No
Instructions:
No official patch exists. Remove or replace the vulnerable software entirely.
🔧 Temporary Workarounds
Implement strict file upload validation
allAdd server-side validation to restrict uploaded files to specific extensions and verify file content types.
Disable PHP execution in upload directories
linuxConfigure web server to prevent PHP execution in directories where user files are uploaded.
For Apache: Add 'php_flag engine off' to .htaccess in upload directory
For Nginx: location ~* \.php$ { deny all; } in upload directory
🧯 If You Can't Patch
- Remove the vulnerable software and replace with a secure alternative
- Implement network segmentation and strict firewall rules to limit access to the vulnerable system
🔍 How to Verify
Check if Vulnerable:
Check if /Online Course Registration/my-profile.php exists and allows file uploads without proper validation. Test by attempting to upload a PHP file with image headers.Check Version:
Check the software version in the application interface or source code comments.Verify Fix Applied:
Verify that PHP files cannot be uploaded or executed in upload directories, and that proper file validation is in place.📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to my-profile.php
- POST requests with .php files to upload endpoints
- Execution of unexpected PHP files in upload directories
Network Indicators:
- HTTP POST requests to /Online%20Course%20Registration/my-profile.php with file uploads
- Unusual outbound connections from web server
SIEM Query:
source="web_logs" AND uri="/Online Course Registration/my-profile.php" AND method="POST" AND (file_extension=".php" OR content_type="application/x-php")