CVE-2021-20682
📋 TL;DR
This vulnerability allows remote attackers with administrative privileges in baserCMS to execute arbitrary operating system commands. It affects baserCMS installations prior to version 4.4.5. Attackers can gain full system control if they obtain administrative credentials.
💻 Affected Systems
- baserCMS
📦 What is this software?
Basercms by Basercms
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise leading to data theft, ransomware deployment, lateral movement, and persistent backdoor installation.
Likely Case
Attackers with stolen admin credentials execute commands to exfiltrate sensitive data, modify content, or install cryptocurrency miners.
If Mitigated
With proper access controls and network segmentation, impact is limited to the baserCMS application server only.
🎯 Exploit Status
Exploitation requires administrative access. Attack vectors are unspecified in public disclosures.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.4.5
Vendor Advisory: https://basercms.net/security/JVN64869876
Restart Required: Yes
Instructions:
1. Backup your baserCMS installation and database. 2. Download baserCMS 4.4.5 or later from official sources. 3. Replace existing files with new version. 4. Run any database migration scripts if provided. 5. Restart web server services.
🔧 Temporary Workarounds
Restrict Admin Access
allLimit administrative access to trusted IP addresses only
# Configure web server (Apache example):
<Location /admin>
Require ip 192.168.1.0/24
</Location>
# Configure web server (Nginx example):
location /admin {
allow 192.168.1.0/24;
deny all;
}
Disable Unused Admin Functions
linuxRemove or disable administrative features not in use
# Remove or rename admin directory if not needed:
mv /path/to/basercms/admin /path/to/basercms/admin_disabled
🧯 If You Can't Patch
- Implement strict network segmentation to isolate baserCMS from critical systems
- Enforce multi-factor authentication for all administrative accounts
🔍 How to Verify
Check if Vulnerable:
Check baserCMS version in administration panel or examine version.php fileCheck Version:
grep -r "BASERCMS_VERSION" /path/to/basercms/version.phpVerify Fix Applied:
Confirm version is 4.4.5 or higher in administration panel📡 Detection & Monitoring
Log Indicators:
- Unusual command execution patterns in web server logs
- Multiple failed admin login attempts followed by successful login
- Suspicious POST requests to administrative endpoints
Network Indicators:
- Outbound connections to suspicious IPs from baserCMS server
- Unusual network traffic patterns from web server
SIEM Query:
source="web_server_logs" AND (uri_path="/admin/*" AND (status=200 OR status=302)) AND (user_agent CONTAINS "curl" OR user_agent CONTAINS "wget" OR user_agent CONTAINS "python")