CVE-2023-39001
📋 TL;DR
This CVE describes a command injection vulnerability in OPNsense's diag_backup.php component that allows attackers to execute arbitrary commands by uploading a malicious backup configuration file. Attackers can achieve remote code execution with high privileges. Affected users include all OPNsense Community Edition users before version 23.7 and Business Edition users before version 23.4.2.
💻 Affected Systems
- OPNsense Community Edition
- OPNsense Business Edition
📦 What is this software?
Opnsense by Opnsense
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root-level access, allowing attackers to install persistent backdoors, exfiltrate sensitive data, pivot to internal networks, or disrupt network operations.
Likely Case
Remote code execution leading to network device compromise, credential theft, and potential lateral movement within the network infrastructure.
If Mitigated
Limited impact if proper network segmentation, file upload restrictions, and least privilege principles are implemented.
🎯 Exploit Status
Exploitation requires authenticated access to the backup functionality. The vulnerability is well-documented with public proof-of-concept details available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Community Edition 23.7+, Business Edition 23.4.2+
Vendor Advisory: https://github.com/opnsense/core/commit/e800097d0c287bb665f0751a98a67c75ef7b45e5
Restart Required: No
Instructions:
1. Log into OPNsense web interface. 2. Navigate to System > Firmware > Updates. 3. Check for and apply available updates. 4. Verify version is updated to Community Edition 23.7+ or Business Edition 23.4.2+.
🔧 Temporary Workarounds
Disable backup functionality
allTemporarily disable the backup functionality until patching can be completed
Restrict backup file uploads
allImplement strict file upload validation and sanitization for backup files
🧯 If You Can't Patch
- Implement strict network segmentation to isolate OPNsense devices from critical internal networks
- Apply strict access controls to limit which users can access the backup functionality
🔍 How to Verify
Check if Vulnerable:
Check OPNsense version via web interface (System > Firmware > Status) or CLI: 'opnsense-version'Check Version:
opnsense-versionVerify Fix Applied:
Verify version is Community Edition 23.7+ or Business Edition 23.4.2+ using same methods📡 Detection & Monitoring
Log Indicators:
- Unusual backup file uploads
- Suspicious commands executed via backup process
- Unexpected system modifications following backup operations
Network Indicators:
- Unusual outbound connections from OPNsense device
- Suspicious traffic patterns from firewall management interface
SIEM Query:
source="opnsense" AND (event="backup_upload" OR event="diag_backup") AND (command="*" OR process="*sh" OR process="*bash")