CVE-2021-21936
📋 TL;DR
This SQL injection vulnerability allows authenticated users or attackers via CSRF to execute arbitrary SQL commands through the 'health_alt_filter' parameter. Successful exploitation could lead to data theft, modification, or deletion. Any system running the affected software with authenticated access is vulnerable.
💻 Affected Systems
- Not specified in provided references
📦 What is this software?
R Seenet by Advantech
⚠️ Risk & Real-World Impact
Worst Case
Complete database compromise including data exfiltration, modification, or deletion, and potential privilege escalation to execute system commands.
Likely Case
Unauthorized data access and potential data manipulation through SQL injection.
If Mitigated
Limited impact with proper input validation and parameterized queries in place.
🎯 Exploit Status
Exploitation requires authenticated access or successful CSRF attack. SQL injection via HTTP parameter manipulation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in provided references
Vendor Advisory: https://talosintelligence.com/vulnerability_reports/TALOS-2021-1366
Restart Required: No
Instructions:
1. Check vendor advisory for specific patch details. 2. Apply security updates for affected software. 3. Validate fix by testing the vulnerable endpoint.
🔧 Temporary Workarounds
Input Validation Filter
allImplement strict input validation for the health_alt_filter parameter
# Web application firewall rule to block SQL injection patterns
# Application-level input sanitization
CSRF Protection
allImplement CSRF tokens to prevent cross-site request forgery attacks
# Add CSRF tokens to all forms and validate on server-side
🧯 If You Can't Patch
- Implement web application firewall with SQL injection rules
- Disable or restrict access to vulnerable endpoint if not required
🔍 How to Verify
Check if Vulnerable:
Test the health_alt_filter parameter with SQL injection payloads in authenticated requestsCheck Version:
# Check software version via vendor-specific commandsVerify Fix Applied:
Retest with SQL injection payloads after patch application; verify parameterized queries are used📡 Detection & Monitoring
Log Indicators:
- Unusual SQL queries in database logs
- Multiple failed authentication attempts followed by SQL injection patterns
- HTTP requests with SQL keywords in health_alt_filter parameter
Network Indicators:
- HTTP POST/GET requests containing SQL injection patterns in parameters
- Unusual database connection patterns from web servers
SIEM Query:
source="web_logs" AND (health_alt_filter CONTAINS "UNION" OR health_alt_filter CONTAINS "SELECT" OR health_alt_filter CONTAINS "INSERT")