CVE-2021-42330
📋 TL;DR
This vulnerability allows authenticated users in the ShinHer StudyOnline System to bypass authorization controls and access/modify other users' credentials and personal information by manipulating URL parameters. It affects all organizations using the vulnerable version of this educational software.
💻 Affected Systems
- ShinHer StudyOnline System
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could compromise all user accounts, steal sensitive personal information, modify grades/credentials, and potentially gain administrative access to the entire system.
Likely Case
Malicious users or compromised accounts would access and modify other users' personal information, potentially leading to identity theft, academic fraud, or privacy violations.
If Mitigated
With proper authorization controls, users would only be able to access and edit their own information as intended.
🎯 Exploit Status
Exploitation requires authenticated access but involves simple URL parameter manipulation. No special tools needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in references but vendor should provide updated version
Vendor Advisory: https://www.twcert.org.tw/tw/cp-132-5200-3d3ca-1.html
Restart Required: Yes
Instructions:
1. Contact ShinHer for patched version
2. Backup current installation
3. Apply vendor-provided patch
4. Restart application services
5. Verify authorization controls work properly
🔧 Temporary Workarounds
Disable Teacher Edit Function
allTemporarily disable the vulnerable Teacher Edit function until patching is complete
# Modify application configuration to disable /teacher/edit endpoint
Implement Web Application Firewall Rules
allAdd WAF rules to block unauthorized parameter manipulation attempts
# Example: Block requests with suspicious user ID parameters in Teacher Edit URLs
🧯 If You Can't Patch
- Implement strict access controls at network level to limit who can access the system
- Enable detailed logging and monitoring for unauthorized access attempts to Teacher Edit function
🔍 How to Verify
Check if Vulnerable:
Test if authenticated users can access other users' data by modifying user ID parameters in Teacher Edit URLsCheck Version:
Check application version in admin panel or configuration filesVerify Fix Applied:
Verify that authorization checks now properly restrict users to only their own data in the Teacher Edit function📡 Detection & Monitoring
Log Indicators:
- Multiple failed authorization attempts
- User accessing Teacher Edit function with different user IDs than their own
- Unusual pattern of data modifications
Network Indicators:
- HTTP requests to Teacher Edit endpoint with manipulated user ID parameters
- Unusual traffic patterns to user data endpoints
SIEM Query:
source="web_logs" AND (url_path="/teacher/edit" AND user_id!=session_user_id)