CVE-2021-26610
📋 TL;DR
CVE-2021-26610 is a remote code execution vulnerability in godomall5's file upload function that lacks proper file extension and authority validation. Attackers can upload malicious files to execute arbitrary code on affected systems. This affects all installations of godomall5 using the vulnerable move_uploaded_file function.
💻 Affected Systems
- godomall5
📦 What is this software?
Godomall5 by Nhn Commerce
Godomall5 by Nhn Commerce
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary commands, steal data, install malware, or pivot to other systems.
Likely Case
Webshell deployment leading to data theft, defacement, or use as a foothold for further attacks.
If Mitigated
Limited impact with proper file upload restrictions and web application firewalls in place.
🎯 Exploit Status
Simple file upload bypass techniques can be used to exploit this vulnerability without authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check vendor advisory for specific patched version
Vendor Advisory: https://www.boho.or.kr/krcert/secNoticeView.do?bulletin_writing_sequence=36304
Restart Required: Yes
Instructions:
1. Check vendor advisory for patched version. 2. Backup current installation. 3. Apply vendor-provided patch. 4. Restart web server. 5. Verify fix implementation.
🔧 Temporary Workarounds
File Upload Restriction
allImplement strict file type validation and extension whitelisting
# Configure web server to only allow specific file types
# Example Apache: <FilesMatch "\.(php|phtml|phar)$">
# Deny from all
# </FilesMatch>
Web Application Firewall Rules
allBlock suspicious file upload patterns
# WAF rule to block file uploads with executable extensions
# Example ModSecurity: SecRule FILES_TMPNAMES "@rx \.(php|phtml|phar|exe|bat|sh)$" "deny,status:403"
🧯 If You Can't Patch
- Disable file upload functionality completely in godomall5
- Implement network segmentation to isolate godomall5 server from critical systems
🔍 How to Verify
Check if Vulnerable:
Test if you can upload files with executable extensions (like .php, .phtml) through godomall5's upload interfaceCheck Version:
Check godomall5 version in admin panel or configuration filesVerify Fix Applied:
Attempt to upload malicious files after patch - should be rejected with proper validation errors📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads with executable extensions
- Multiple failed upload attempts
- Webshell access patterns in access logs
Network Indicators:
- POST requests to upload endpoints with suspicious file names
- Outbound connections from web server to unknown IPs
SIEM Query:
source="web_logs" AND (uri="*upload*" OR uri="*move_uploaded*" OR method="POST") AND (filename="*.php" OR filename="*.phtml" OR filename="*.phar")