CVE-2021-31314
📋 TL;DR
This vulnerability in ejinshan v8+ terminal security system allows attackers to upload arbitrary files to arbitrary server locations due to insufficient file upload validation. It affects organizations using this security software, potentially compromising their endpoint protection systems. Attackers can exploit this to achieve remote code execution or system takeover.
💻 Affected Systems
- ejinshan terminal security system
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise leading to ransomware deployment, data exfiltration, or establishment of persistent backdoors across the network.
Likely Case
Web shell upload leading to lateral movement, credential theft, and installation of additional malware on affected systems.
If Mitigated
File upload attempts are blocked or logged, preventing successful exploitation while maintaining system functionality.
🎯 Exploit Status
Exploitation requires authentication to the web interface, but the vulnerability is straightforward to exploit once authenticated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Specific version not publicly documented in references
Vendor Advisory: Not provided in references
Restart Required: Yes
Instructions:
1. Contact ejinshan vendor for latest security patches. 2. Apply the patch to all affected systems. 3. Restart the security service or system. 4. Verify the patch is applied correctly.
🔧 Temporary Workarounds
Restrict File Upload Types
allConfigure the web application to only accept specific, safe file types and validate file extensions server-side.
Implement Web Application Firewall Rules
allDeploy WAF rules to block suspicious file upload patterns and malicious file types.
🧯 If You Can't Patch
- Isolate affected systems from critical network segments and internet access
- Implement strict network segmentation and monitor for unusual file upload activities
🔍 How to Verify
Check if Vulnerable:
Test if the web interface allows uploading files with dangerous extensions (e.g., .jsp, .php, .aspx) to arbitrary directories.Check Version:
Check the software version through the web interface or system documentation.Verify Fix Applied:
Attempt to upload malicious files after patching; successful blocking indicates the fix is working.📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to non-standard directories
- Multiple failed upload attempts
- Uploads of executable file types
Network Indicators:
- HTTP POST requests with file uploads to vulnerable endpoints
- Traffic to newly created web shells
SIEM Query:
source="web_logs" AND (uri CONTAINS "/upload" OR method="POST") AND (file_extension IN ("jsp", "php", "aspx", "exe"))