CVE-2021-41691
📋 TL;DR
This SQL injection vulnerability in OS4Ed OpenSIS allows attackers to execute arbitrary SQL commands through manipulated student_id and TRANSFER{SCHOOL] parameters. It affects all users of OpenSIS Community Edition v8.0, potentially compromising student information systems.
💻 Affected Systems
- OS4Ed Open Source Information System Community Edition
📦 What is this software?
Opensis by Os4ed
⚠️ Risk & Real-World Impact
Worst Case
Complete database compromise leading to data theft, data manipulation, or full system takeover via SQL injection to RCE chaining.
Likely Case
Unauthorized access to sensitive student records, grades, personal information, and potential data exfiltration.
If Mitigated
Limited impact with proper input validation and WAF rules blocking SQL injection patterns.
🎯 Exploit Status
SQL injection via POST parameters requires minimal technical skill to exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v8.0.1 or later
Vendor Advisory: https://opensis.com/
Restart Required: No
Instructions:
1. Backup database and application files. 2. Download latest version from official repository. 3. Replace vulnerable files with patched versions. 4. Test functionality.
🔧 Temporary Workarounds
Input Validation Filter
allAdd parameter validation to block SQL injection patterns
Modify /TransferredOutModal.php to validate student_id as integer and sanitize TRANSFER{SCHOOL] parameter
WAF Rule
allImplement web application firewall rules to block SQL injection attempts
Add rule to block requests containing SQL keywords in POST parameters to /TransferredOutModal.php
🧯 If You Can't Patch
- Restrict access to /TransferredOutModal.php to authorized users only
- Implement network segmentation to isolate OpenSIS from sensitive systems
🔍 How to Verify
Check if Vulnerable:
Test POST request to /TransferredOutModal.php with SQL injection payload in student_id parameterCheck Version:
Check OpenSIS version in admin panel or configuration filesVerify Fix Applied:
Verify parameter validation rejects SQL injection attempts and check version is v8.0.1+📡 Detection & Monitoring
Log Indicators:
- Unusual SQL errors in application logs
- Multiple failed login attempts followed by POST to /TransferredOutModal.php
Network Indicators:
- POST requests to /TransferredOutModal.php containing SQL keywords like UNION, SELECT, INSERT
SIEM Query:
source="web_logs" AND uri="/TransferredOutModal.php" AND (student_id="*UNION*" OR student_id="*SELECT*")