CVE-2023-31211
📋 TL;DR
This vulnerability in Checkmk allows attackers to use locked credentials due to insufficient authentication flow. Attackers could potentially gain unauthorized access to monitoring systems. Affected are Checkmk installations before versions 2.2.0p18, 2.1.0p38, and 2.0.0p39.
💻 Affected Systems
- Checkmk
📦 What is this software?
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⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of monitoring system leading to data exfiltration, system manipulation, or lateral movement to other systems.
Likely Case
Unauthorized access to monitoring data and potential privilege escalation within the Checkmk environment.
If Mitigated
Limited impact with proper network segmentation and strong authentication controls in place.
🎯 Exploit Status
Exploitation requires some authentication knowledge but is technically straightforward once understood.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.2.0p18, 2.1.0p38, or 2.0.0p39
Vendor Advisory: https://checkmk.com/werk/16227
Restart Required: Yes
Instructions:
1. Backup your Checkmk configuration. 2. Update to the patched version using your package manager. 3. Restart Checkmk services. 4. Verify the update was successful.
🔧 Temporary Workarounds
Network Access Restriction
linuxRestrict network access to Checkmk instances to trusted IP addresses only.
iptables -A INPUT -p tcp --dport 80 -s trusted_ip -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s trusted_ip -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Checkmk instances
- Enable multi-factor authentication and review all user accounts
🔍 How to Verify
Check if Vulnerable:
Check Checkmk version: omd versionCheck Version:
omd versionVerify Fix Applied:
Verify version is 2.2.0p18, 2.1.0p38, or 2.0.0p39 or later📡 Detection & Monitoring
Log Indicators:
- Unusual authentication attempts
- Access from unexpected IP addresses
- Multiple failed login attempts followed by success
Network Indicators:
- Unusual traffic patterns to Checkmk ports
- Authentication requests from unauthorized sources
SIEM Query:
source="checkmk.log" AND ("authentication" OR "login") AND status="success" AND src_ip NOT IN [trusted_ips]