CVE-2023-6017
📋 TL;DR
This vulnerability in H2O allows attackers to take over S3 bucket URLs by exploiting a reference to a bucket that no longer exists. This affects systems using H2O with S3 bucket configurations. Attackers could redirect traffic or serve malicious content through the compromised URL.
💻 Affected Systems
- H2O
📦 What is this software?
H2o by H2o
⚠️ Risk & Real-World Impact
Worst Case
Complete takeover of S3 bucket URL allowing data exfiltration, malware distribution, or phishing attacks through legitimate-looking URLs.
Likely Case
Redirecting users to malicious sites or serving compromised content through the hijacked URL.
If Mitigated
Limited impact with proper URL validation and monitoring in place, potentially just broken links.
🎯 Exploit Status
Exploitation requires identifying abandoned S3 bucket references and registering the bucket name.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check H2O repository for latest security updates
Vendor Advisory: https://huntr.com/bounties/6a69952f-a1ba-4dee-9d8c-e87f52508b58
Restart Required: Yes
Instructions:
1. Update H2O to latest patched version. 2. Review and update all S3 bucket references in configuration. 3. Restart H2O service.
🔧 Temporary Workarounds
Remove S3 bucket references
allTemporarily disable or remove S3 bucket configurations from H2O
Edit H2O configuration files to comment out or remove S3 bucket references
Implement URL validation
allAdd validation for all external URLs in configuration
Implement custom validation scripts for configuration files
🧯 If You Can't Patch
- Monitor for suspicious URL redirects or unexpected S3 bucket access
- Implement network controls to block traffic to suspicious S3 endpoints
🔍 How to Verify
Check if Vulnerable:
Review H2O configuration files for S3 bucket references and check if referenced buckets existCheck Version:
h2o --versionVerify Fix Applied:
Verify configuration files no longer contain references to non-existent S3 buckets📡 Detection & Monitoring
Log Indicators:
- Failed S3 bucket connections
- Unexpected URL redirects
- Access to newly registered S3 domains
Network Indicators:
- Traffic to suspicious S3 endpoints
- DNS queries for previously unused bucket names
SIEM Query:
source="h2o" AND (error="S3" OR url_redirect="s3")