CVE-2020-27996
📋 TL;DR
This vulnerability in SmartStoreNET allows attackers to bypass security controls through improper handling of CustomModelPartAttribute decorations in ModelBase.CustomProperties. It affects all SmartStoreNET installations before version 4.0.1. Attackers could potentially execute unauthorized actions or access restricted functionality.
💻 Affected Systems
- SmartStoreNET
📦 What is this software?
Smartstorenet by Smartstore
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through remote code execution or administrative privilege escalation
Likely Case
Unauthorized data access, privilege escalation, or manipulation of application functionality
If Mitigated
Limited impact with proper input validation and access controls in place
🎯 Exploit Status
Exploitation requires understanding of SmartStoreNET's model binding system but no authentication is needed
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.0.1
Vendor Advisory: https://github.com/smartstore/SmartStoreNET/commit/8702c6140f4fc91956ef35dba12d24492fb3f768
Restart Required: Yes
Instructions:
1. Backup your current installation. 2. Download SmartStoreNET 4.0.1 or later. 3. Replace all files with the new version. 4. Restart the application/web server. 5. Verify functionality.
🔧 Temporary Workarounds
Input Validation Enhancement
allImplement additional input validation for CustomProperties model binding
Not applicable - requires code modifications
🧯 If You Can't Patch
- Implement strict WAF rules to block suspicious model binding requests
- Restrict network access to SmartStoreNET instances and implement network segmentation
🔍 How to Verify
Check if Vulnerable:
Check SmartStoreNET version in admin panel or web.config file for version number below 4.0.1Check Version:
Check Admin → System → System Info in SmartStoreNET dashboardVerify Fix Applied:
Verify version is 4.0.1 or higher and test model binding functionality📡 Detection & Monitoring
Log Indicators:
- Unusual model binding requests
- Multiple failed authentication attempts with custom properties
- Unexpected CustomModelPartAttribute usage
Network Indicators:
- HTTP requests manipulating CustomProperties parameters
- Unusual POST requests to model binding endpoints
SIEM Query:
web_requests WHERE (uri CONTAINS 'CustomProperties' OR parameters CONTAINS 'CustomModelPart') AND status_code = 200🔗 References
- https://github.com/smartstore/SmartStoreNET/commit/8702c6140f4fc91956ef35dba12d24492fb3f768
- https://github.com/smartstore/SmartStoreNET/compare/4.0.0...4.0.1
- https://securitylab.github.com/advisories/GHSL-2020-138-139-SmartstoreAG-SmartStoreNET
- https://github.com/smartstore/SmartStoreNET/commit/8702c6140f4fc91956ef35dba12d24492fb3f768
- https://github.com/smartstore/SmartStoreNET/compare/4.0.0...4.0.1
- https://securitylab.github.com/advisories/GHSL-2020-138-139-SmartstoreAG-SmartStoreNET
