CVE-2021-40956
📋 TL;DR
CVE-2021-40956 is an SQL injection vulnerability in LaiKetui v3.5.0's background menu management function that allows attackers to execute arbitrary SQL commands. This affects administrators and users with access to the vulnerable background interface. Successful exploitation can lead to unauthorized access to sensitive database information.
💻 Affected Systems
- LaiKetui
📦 What is this software?
Laiketui by Laiketui
⚠️ Risk & Real-World Impact
Worst Case
Complete database compromise including exfiltration of all sensitive data (user credentials, payment information, business data), potential privilege escalation to system-level access, and possible remote code execution.
Likely Case
Unauthorized access to sensitive business data, user information theft, and potential modification of application data through SQL injection.
If Mitigated
Limited impact with proper input validation and parameterized queries in place, potentially only allowing limited data viewing without modification capabilities.
🎯 Exploit Status
Exploitation requires access to the background interface. SQL injection techniques are well-documented and tools like sqlmap can automate exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version after v3.5.0
Vendor Advisory: https://github.com/bettershop/LaikeTui/issues/13
Restart Required: Yes
Instructions:
1. Upgrade to the latest version of LaiKetui. 2. Apply any available security patches from the vendor. 3. Restart the application service. 4. Verify the fix by testing the vulnerable endpoint.
🔧 Temporary Workarounds
Input Validation and Sanitization
allImplement strict input validation and parameterized queries for the menu management function
Implement prepared statements in PHP: $stmt = $pdo->prepare('SELECT * FROM menu WHERE id = ?'); $stmt->execute([$id]);
Access Restriction
linuxRestrict access to the admin interface using network controls and strong authentication
iptables -A INPUT -p tcp --dport [admin_port] -s [trusted_ips] -j ACCEPT
iptables -A INPUT -p tcp --dport [admin_port] -j DROP
🧯 If You Can't Patch
- Implement a Web Application Firewall (WAF) with SQL injection rules
- Restrict database user permissions to minimum required privileges
🔍 How to Verify
Check if Vulnerable:
Test the menu management endpoint with SQL injection payloads like ' OR '1'='1 in parametersCheck Version:
Check LaiKetui version in admin panel or configuration filesVerify Fix Applied:
Attempt SQL injection on the patched endpoint and verify it rejects malicious input📡 Detection & Monitoring
Log Indicators:
- Unusual SQL queries in database logs
- Multiple failed login attempts to admin interface
- Unexpected database access patterns
Network Indicators:
- SQL keywords in HTTP requests to admin endpoints
- Unusual traffic patterns to database ports
SIEM Query:
source="web_logs" AND (url="*admin/menu*" AND (request="*SELECT*" OR request="*UNION*" OR request="*OR 1=1*"))