CVE-2020-20067
📋 TL;DR
CVE-2020-20067 is a file upload vulnerability in ebCMS v1.1.0 that allows remote attackers to upload malicious files and execute arbitrary code on the server. This affects all systems running the vulnerable version of ebCMS content management system.
💻 Affected Systems
- ebCMS
📦 What is this software?
Ebcms by Ebcms
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the web server, data exfiltration, and lateral movement to other systems.
Likely Case
Webshell deployment leading to data theft, defacement, or use as a foothold for further attacks.
If Mitigated
Attack blocked at web application firewall or file upload validation layer with no impact.
🎯 Exploit Status
The vulnerability is in the upload type parameter, making exploitation straightforward for attackers with basic web penetration testing skills.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.1.1 or later
Vendor Advisory: https://github.com/a932278490/ebcms/issues/1
Restart Required: No
Instructions:
1. Backup your current installation. 2. Download and install ebCMS version 1.1.1 or later from the official repository. 3. Verify the upload functionality works correctly with proper file type validation.
🔧 Temporary Workarounds
Implement File Upload Restrictions
allAdd server-side validation to restrict uploads to specific file types and extensions
Web Application Firewall Rules
allConfigure WAF to block requests containing suspicious upload parameters or file extensions
🧯 If You Can't Patch
- Disable file upload functionality completely in the application
- Implement strict file type validation and store uploaded files outside web root directory
🔍 How to Verify
Check if Vulnerable:
Check if running ebCMS version 1.1.0 by examining the application version in admin panel or source codeCheck Version:
Check application configuration files or admin interface for version informationVerify Fix Applied:
Test file upload functionality with malicious file types to ensure they are rejected📡 Detection & Monitoring
Log Indicators:
- Unusual file upload attempts with non-standard extensions
- Multiple failed upload attempts followed by successful suspicious upload
Network Indicators:
- HTTP POST requests to upload endpoints with unusual file types
- Subsequent connections to uploaded files with executable extensions
SIEM Query:
source="web_server" AND (method="POST" AND uri="*upload*" AND (file_extension="php" OR file_extension="jsp" OR file_extension="asp"))