CVE-2021-42580
📋 TL;DR
CVE-2021-42580 is a critical vulnerability in Sourcecodester Online Learning System 2.0 that combines SQL injection authentication bypass with authenticated file upload to achieve unauthenticated remote code execution. Attackers can exploit this to gain administrative access and execute arbitrary commands on the server. All deployments of this specific software version are affected.
💻 Affected Systems
- Sourcecodester Online Learning System
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary commands, steal sensitive data, install malware, pivot to other systems, and maintain persistent access.
Likely Case
Unauthenticated attackers gain administrative access, upload malicious files, and execute commands to deface websites, steal database contents, or deploy ransomware.
If Mitigated
With proper network segmentation and web application firewalls, exploitation attempts are blocked, limiting impact to the web application layer only.
🎯 Exploit Status
Multiple public exploit scripts available. Attack chain combines SQL injection in /admin/login.php with file upload in Master.php.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: Not available
Restart Required: No
Instructions:
No official patch available. Consider migrating to alternative software or implementing comprehensive workarounds.
🔧 Temporary Workarounds
Web Application Firewall Rules
allImplement WAF rules to block SQL injection patterns and restrict file uploads to admin directory
# ModSecurity rules example:
SecRule ARGS "(?i:(union|select|insert|update|delete|drop|exec|xp_cmdshell))" \
"id:1001,phase:2,deny,status:403,msg:'SQL Injection attempt'"
# Block file uploads to Master.php:
SecRule REQUEST_FILENAME "@endsWith Master.php" \
"id:1002,phase:1,deny,status:403,msg:'Blocked Master.php access'"
File Upload Restrictions
allRestrict file uploads to specific extensions and implement file type verification
# PHP configuration to restrict uploads:
$allowed_extensions = array('jpg', 'png', 'pdf');
$file_extension = strtolower(pathinfo($_FILES['file']['name'], PATHINFO_EXTENSION));
if (!in_array($file_extension, $allowed_extensions)) {
die('Invalid file type');
}
🧯 If You Can't Patch
- Immediately isolate the system from internet access and place behind strict firewall rules
- Implement network segmentation to limit lateral movement if compromised
🔍 How to Verify
Check if Vulnerable:
Check if /admin/login.php exists and test for SQL injection using payloads like ' OR '1'='1. Also verify Master.php accepts file uploads without proper authentication.Check Version:
Check version in application files or database configuration. Look for version indicators in source code or admin panel.Verify Fix Applied:
Test that SQL injection payloads no longer bypass authentication and file uploads to Master.php require proper authentication.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts with SQL patterns in /admin/login.php
- File uploads to Master.php from unauthenticated IPs
- Unusual POST requests containing UNION SELECT or file upload parameters
Network Indicators:
- HTTP requests with SQL injection patterns in login parameters
- File uploads to Master.php endpoint
- Subsequent connections to uploaded malicious files
SIEM Query:
source="web_logs" AND (uri="/admin/login.php" AND (message="*union*" OR message="*select*" OR message="*' OR '*")) OR (uri="*Master.php*" AND method="POST" AND size>100000)🔗 References
- http://packetstormsecurity.com/files/164985/Online-Learning-System-2.0-Remote-Code-Execution.html
- https://github.com/DjebbarAnon/online-learning-system-v2-sqli-authentication-bypass-file-upload-unauthenticated-RCE
- https://github.com/nu11secur1ty/CVE-nu11secur1ty/tree/main/vendors/oretnom23/CVE-nu11-07
- https://www.nu11secur1ty.com/2021/09/cve-nu11-07-elearning-v2by-oretnom23-is.html
- https://www.nu11secur1ty.com/2021/11/cve-2021-42580.html
- http://packetstormsecurity.com/files/164985/Online-Learning-System-2.0-Remote-Code-Execution.html
- https://github.com/DjebbarAnon/online-learning-system-v2-sqli-authentication-bypass-file-upload-unauthenticated-RCE
- https://github.com/nu11secur1ty/CVE-nu11secur1ty/tree/main/vendors/oretnom23/CVE-nu11-07
- https://www.nu11secur1ty.com/2021/09/cve-nu11-07-elearning-v2by-oretnom23-is.html
- https://www.nu11secur1ty.com/2021/11/cve-2021-42580.html
