CVE-2021-46063
📋 TL;DR
MCMS v5.2.5 contains a Server-Side Template Injection (SSTI) vulnerability in the Template Management module that allows attackers to execute arbitrary code on the server. This affects all systems running MCMS v5.2.5 with the vulnerable module enabled. Attackers can potentially gain full control of affected systems.
💻 Affected Systems
- MCMS
📦 What is this software?
Mcms by Mingsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing remote code execution, data theft, privilege escalation, and lateral movement within the network.
Likely Case
Remote code execution leading to web server compromise, data exfiltration, and potential ransomware deployment.
If Mitigated
Limited impact with proper network segmentation, but still potential for web application compromise.
🎯 Exploit Status
Exploitation requires access to Template Management functionality. Public proof-of-concept exists in GitHub issues.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v5.2.6 or later
Vendor Advisory: https://github.com/ming-soft/MCMS/issues/59
Restart Required: Yes
Instructions:
1. Backup your MCMS installation and database. 2. Download MCMS v5.2.6 or later from official repository. 3. Replace vulnerable files with patched version. 4. Restart web server and MCMS application.
🔧 Temporary Workarounds
Disable Template Management Module
allTemporarily disable or restrict access to the vulnerable Template Management module
# Modify MCMS configuration to disable template management
# Check MCMS documentation for module disabling procedures
Input Validation Filter
allImplement strict input validation for template parameters
# Add input sanitization in template processing functions
# Filter special characters and template syntax
🧯 If You Can't Patch
- Implement strict network segmentation to isolate MCMS from critical systems
- Deploy web application firewall (WAF) with SSTI protection rules
🔍 How to Verify
Check if Vulnerable:
Check MCMS version in admin panel or configuration files. If version is exactly 5.2.5, system is vulnerable.Check Version:
# Check MCMS version in configuration: grep -r 'version' /path/to/mcms/config/ OR check admin dashboardVerify Fix Applied:
Verify MCMS version is 5.2.6 or later and test template management functionality with malicious payloads.📡 Detection & Monitoring
Log Indicators:
- Unusual template file modifications
- Template management requests with suspicious payloads
- System command execution in web logs
Network Indicators:
- HTTP requests to template management endpoints with template syntax payloads
- Outbound connections from web server to unexpected destinations
SIEM Query:
source="web_logs" AND (uri="*template*" OR uri="*manage*" OR method="POST") AND (content="${*}" OR content="<%*" OR content="#*" OR content="*exec*" OR content="*system*")