CVE-2023-6016
📋 TL;DR
CVE-2023-6016 allows remote attackers to execute arbitrary code on H2O dashboard servers through insecure deserialization in the POJO model import feature. This affects any organization using vulnerable versions of H2O with the dashboard exposed. The vulnerability requires no authentication and has a critical CVSS score of 9.8.
💻 Affected Systems
- H2O
📦 What is this software?
H2o by H2o
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise leading to data theft, lateral movement, ransomware deployment, or persistent backdoor installation.
Likely Case
Remote code execution leading to data exfiltration, cryptocurrency mining, or botnet recruitment.
If Mitigated
Attack blocked at network perimeter or through input validation, resulting in no impact.
🎯 Exploit Status
Proof-of-concept exploit is publicly available on huntr.com. Exploitation is straightforward due to insecure deserialization.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.44.0.1
Vendor Advisory: https://huntr.com/bounties/83dd17ec-053e-453c-befb-7d6736bf1836
Restart Required: Yes
Instructions:
1. Upgrade H2O to version 3.44.0.1 or later. 2. Restart the H2O service. 3. Verify the dashboard is no longer vulnerable.
🔧 Temporary Workarounds
Disable POJO Model Import
allDisable the vulnerable POJO model import feature if not required.
Modify H2O configuration to disable POJO import feature
Network Access Control
allRestrict access to H2O dashboard to trusted IP addresses only.
Configure firewall rules to limit dashboard access
🧯 If You Can't Patch
- Implement strict network segmentation to isolate H2O servers from sensitive systems
- Deploy web application firewall (WAF) with deserialization attack detection rules
🔍 How to Verify
Check if Vulnerable:
Check H2O version. If version is below 3.44.0.1 and dashboard is accessible, assume vulnerable.Check Version:
Check H2O dashboard interface or configuration files for version informationVerify Fix Applied:
Verify H2O version is 3.44.0.1 or higher and test POJO import functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual POJO model import attempts
- Large serialized object uploads
- Java deserialization errors
Network Indicators:
- HTTP POST requests to POJO import endpoints with serialized Java objects
SIEM Query:
source="h2o" AND (event="pojo_import" OR event="deserialization")