CVE-2024-8606
📋 TL;DR
This vulnerability allows authenticated users in Checkmk monitoring systems to bypass two-factor authentication (2FA) via the REST API. Attackers with valid credentials can access protected resources without providing the required second authentication factor. This affects organizations using Checkmk versions before the patched releases.
💻 Affected Systems
- Checkmk
📦 What is this software?
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⚠️ Risk & Real-World Impact
Worst Case
Attackers with stolen credentials gain full administrative access to monitoring systems, potentially modifying alerts, disabling monitoring, or accessing sensitive infrastructure data.
Likely Case
Privilege escalation where authenticated users bypass 2FA to access administrative functions they shouldn't have access to.
If Mitigated
Limited impact if strong network segmentation, proper credential management, and additional authentication layers are in place.
🎯 Exploit Status
Exploitation requires valid user credentials but bypasses the 2FA requirement. The vulnerability is in the authentication flow logic.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Checkmk 2.3.0p16 or 2.2.0p34
Vendor Advisory: https://checkmk.com/werk/16218
Restart Required: Yes
Instructions:
1. Backup your Checkmk configuration. 2. Update to Checkmk 2.3.0p16 (for 2.3.x branch) or 2.2.0p34 (for 2.2.x branch). 3. Restart Checkmk services. 4. Verify 2FA is working correctly.
🔧 Temporary Workarounds
Disable REST API access
linuxTemporarily disable REST API access if not required, forcing all authentication through the web interface.
omd config set APACHE_TCP_ADDR 127.0.0.1
omd restart apache
Restrict API network access
linuxUse firewall rules to restrict REST API access to trusted IP addresses only.
iptables -A INPUT -p tcp --dport 5000 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 5000 -j DROP
🧯 If You Can't Patch
- Implement network segmentation to isolate Checkmk systems from untrusted networks.
- Enforce strict credential policies including regular password rotation and monitoring for credential misuse.
🔍 How to Verify
Check if Vulnerable:
Check Checkmk version: omd version. If version is below 2.3.0p16 (for 2.3.x) or 2.2.0p34 (for 2.2.x), system is vulnerable.Check Version:
omd versionVerify Fix Applied:
After patching, test 2FA functionality by attempting to authenticate via REST API with valid credentials but without 2FA token - this should fail.📡 Detection & Monitoring
Log Indicators:
- REST API authentication attempts without 2FA tokens
- Multiple failed 2FA attempts followed by successful authentication
- Authentication logs showing user access without proper 2FA validation
Network Indicators:
- Unusual REST API traffic patterns
- Authentication requests bypassing expected 2FA flow
SIEM Query:
source="checkmk" AND (event="api_auth" AND NOT token_used="2fa") OR (event="auth_success" AND auth_method!="2fa")