CVE-2021-40353
📋 TL;DR
This is a critical SQL injection vulnerability in openSIS version 8.0 when using MySQL or MariaDB databases. Attackers can inject malicious SQL commands through the USERNAME parameter in index.php, potentially allowing them to access, modify, or delete sensitive student and administrative data. This affects all openSIS 8.0 installations with MySQL/MariaDB backends.
💻 Affected Systems
- openSIS
📦 What is this software?
Opensis by Os4ed
⚠️ Risk & Real-World Impact
Worst Case
Complete database compromise leading to data theft, data destruction, authentication bypass, and potential remote code execution on the database server.
Likely Case
Unauthorized access to sensitive student records, grades, personal information, and administrative data with potential for data exfiltration.
If Mitigated
Limited impact with proper input validation and parameterized queries preventing successful injection attempts.
🎯 Exploit Status
Public proof-of-concept code exists on GitHub. The vulnerability is in the login mechanism, making it accessible without authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown - check for updates beyond version 8.0
Vendor Advisory: https://www.opensis.com/download/english
Restart Required: No
Instructions:
1. Check openSIS website for updated versions. 2. If no patch exists, implement workarounds. 3. Consider upgrading to a newer major version if available.
🔧 Temporary Workarounds
Input Validation Filter
allAdd server-side validation to sanitize USERNAME parameter input
Modify index.php to add: $username = mysqli_real_escape_string($connection, $_POST['USERNAME']);
Web Application Firewall Rule
allBlock SQL injection patterns in USERNAME parameter
WAF rule: Detect and block patterns like ' OR '1'='1, UNION SELECT, --, #, ;
🧯 If You Can't Patch
- Implement network segmentation to isolate openSIS from other critical systems
- Enable detailed logging and monitoring for SQL injection attempts on the USERNAME parameter
🔍 How to Verify
Check if Vulnerable:
Test with SQL injection payload in USERNAME field: ' OR '1'='1Check Version:
Check openSIS version in admin panel or configuration filesVerify Fix Applied:
Attempt SQL injection after implementing fixes - should receive error or be blocked📡 Detection & Monitoring
Log Indicators:
- Unusual SQL errors in application logs
- Multiple failed login attempts with SQL patterns in username field
- Database query errors containing injection patterns
Network Indicators:
- HTTP POST requests to index.php with SQL keywords in USERNAME parameter
- Unusual database connection patterns from web server
SIEM Query:
source="web_logs" AND uri="/index.php" AND (USERNAME CONTAINS "' OR" OR USERNAME CONTAINS "UNION" OR USERNAME CONTAINS "--" OR USERNAME CONTAINS ";")