CVE-2023-49930
📋 TL;DR
CVE-2023-49930 is an improper access control vulnerability in Couchbase Server that allows unauthenticated attackers to execute arbitrary code via cURL calls to the /diag/eval endpoint. This affects all Couchbase Server deployments before version 7.2.4 that have the diagnostic endpoint accessible.
💻 Affected Systems
- Couchbase Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing remote code execution, data exfiltration, and lateral movement within the network.
Likely Case
Remote code execution leading to data theft, service disruption, or deployment of malware/ransomware.
If Mitigated
No impact if endpoint is properly restricted or system is patched.
🎯 Exploit Status
Simple HTTP request to vulnerable endpoint can trigger exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.2.4 and later
Vendor Advisory: https://docs.couchbase.com/server/current/release-notes/relnotes.html
Restart Required: Yes
Instructions:
1. Backup Couchbase configuration and data. 2. Download and install Couchbase Server 7.2.4 or later. 3. Restart Couchbase services. 4. Verify upgrade completed successfully.
🔧 Temporary Workarounds
Restrict access to /diag/eval endpoint
linuxBlock network access to the vulnerable diagnostic endpoint using firewall rules or network segmentation.
iptables -A INPUT -p tcp --dport 8091 -m string --string '/diag/eval' --algo bm -j DROP
Disable diagnostic endpoints
allConfigure Couchbase to disable diagnostic endpoints if not required.
curl -X POST -u Administrator:password http://localhost:8091/diag/eval -d 'ns_config:set(diag_eval_enabled, false).'
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Couchbase servers from untrusted networks.
- Deploy web application firewall (WAF) rules to block requests containing '/diag/eval' in the URL path.
🔍 How to Verify
Check if Vulnerable:
Check Couchbase Server version and verify if /diag/eval endpoint responds to unauthenticated requests.Check Version:
curl -s http://localhost:8091/pools | grep -o '"version":"[^"]*"'Verify Fix Applied:
Confirm version is 7.2.4+ and test that /diag/eval endpoint rejects unauthenticated requests.📡 Detection & Monitoring
Log Indicators:
- HTTP requests to /diag/eval endpoint
- Unusual process execution from Couchbase service account
Network Indicators:
- HTTP POST requests to port 8091 with /diag/eval in URL
- Unusual outbound connections from Couchbase server
SIEM Query:
source="couchbase.log" AND (url_path="/diag/eval" OR "diag_eval")