CVE-2023-30797
📋 TL;DR
This vulnerability in Netflix Lemur allows attackers to guess default credentials due to insufficient randomness in generation. Attackers could gain unauthorized access to certificate management resources. Organizations using Lemur versions before 1.3.2 with default credentials are affected.
💻 Affected Systems
- Netflix Lemur
📦 What is this software?
Lemur by Netflix
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of certificate management infrastructure, allowing attackers to issue fraudulent certificates, intercept encrypted traffic, or impersonate services.
Likely Case
Unauthorized access to certificate management interface leading to certificate theft or unauthorized issuance.
If Mitigated
Limited impact if custom credentials are used or if the system is isolated from external networks.
🎯 Exploit Status
Exploitation requires guessing default credentials, which is trivial due to weak randomness. No authentication needed to attempt credential guessing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.3.2
Vendor Advisory: https://github.com/Netflix/lemur/security/advisories/GHSA-5fqv-mpj8-h7gm
Restart Required: Yes
Instructions:
1. Backup current configuration and data. 2. Stop Lemur service. 3. Upgrade to version 1.3.2 or later using package manager or manual installation. 4. Restart Lemur service. 5. Regenerate any default credentials created by vulnerable versions.
🔧 Temporary Workarounds
Change Default Credentials
allReplace all default credentials with strong, randomly generated credentials
# Use Lemur's credential management to change default admin and service credentials
# Ensure new passwords are at least 16 characters with mixed character types
Network Isolation
linuxRestrict network access to Lemur instances
# Configure firewall rules to allow only trusted IPs
iptables -A INPUT -p tcp --dport 8000 -s trusted_ip_range -j ACCEPT
iptables -A INPUT -p tcp --dport 8000 -j DROP
🧯 If You Can't Patch
- Immediately change all default credentials to strong, unique passwords
- Implement network segmentation and restrict access to Lemur instances to only trusted administrative networks
🔍 How to Verify
Check if Vulnerable:
Check Lemur version and verify if default credentials were generated by versions before 1.3.2. Review credential generation logs for weak randomness indicators.Check Version:
lemur --version # or check package manager: dpkg -l | grep lemur # or rpm -qa | grep lemurVerify Fix Applied:
Confirm version is 1.3.2 or later and verify new credentials are properly generated with strong randomness.📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts from single source
- Successful logins with default credential patterns
- Credential generation events with predictable values
Network Indicators:
- Brute force authentication attempts on Lemur ports
- Unusual certificate issuance or management activities
SIEM Query:
source="lemur.log" ("authentication failed" OR "login attempt") | stats count by src_ip | where count > 10🔗 References
- https://github.com/Netflix/lemur/commit/666d853212174ee7f4e6f8b3b4b389ede1872238
- https://github.com/Netflix/lemur/security/advisories/GHSA-5fqv-mpj8-h7gm
- https://github.com/Netflix/security-bulletins/blob/master/advisories/nflx-2023-001.md
- https://vulncheck.com/advisories/netflix-lemur-weak-rng
- https://github.com/Netflix/lemur/commit/666d853212174ee7f4e6f8b3b4b389ede1872238
- https://github.com/Netflix/lemur/security/advisories/GHSA-5fqv-mpj8-h7gm
- https://github.com/Netflix/security-bulletins/blob/master/advisories/nflx-2023-001.md
- https://vulncheck.com/advisories/netflix-lemur-weak-rng
