CVE-2023-28354
📋 TL;DR
CVE-2023-28354 is a critical remote code execution vulnerability in Opsview Monitor Agent 6.8 that allows unauthenticated attackers to execute arbitrary commands as SYSTEM on Windows systems. Attackers can exploit this by sending specially crafted NRPE plugin requests to vulnerable installations. Organizations running Opsview Monitor Agent 6.8 with default configurations are affected.
💻 Affected Systems
- Opsview Monitor Agent
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, allowing attackers to install malware, steal credentials, pivot to other systems, and maintain persistent access.
Likely Case
Attackers gain SYSTEM-level command execution, enabling them to deploy ransomware, exfiltrate sensitive data, or use the compromised system as a foothold for lateral movement.
If Mitigated
With proper network segmentation and access controls, impact is limited to the affected system only, preventing lateral movement and data exfiltration.
🎯 Exploit Status
Public proof-of-concept code is available on GitHub. The exploit requires minimal technical skill as it involves sending crafted NRPE requests to the vulnerable service.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.8.2 or later
Vendor Advisory: https://www.opsview.com/support/knowledge-base/security-advisory-opsview-monitor-agent-cve-2023-28354
Restart Required: Yes
Instructions:
1. Download Opsview Monitor Agent version 6.8.2 or later from the official vendor site. 2. Stop the Opsview Monitor Agent service. 3. Install the updated version. 4. Restart the service. 5. Verify the installation by checking the agent version.
🔧 Temporary Workarounds
Disable NRPE Plugin Command Control Characters
linuxModify NRPE configuration to prevent command control characters from being passed to command-line interpreters.
Edit nrpe.cfg and set 'dont_blame_nrpe=0'
Restart NRPE service: systemctl restart nrpe
Network Access Control
allRestrict network access to the NRPE service port (default 5666) to trusted management systems only.
Windows: netsh advfirewall firewall add rule name="Block NRPE" dir=in action=block protocol=TCP localport=5666
Linux: iptables -A INPUT -p tcp --dport 5666 -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Opsview Monitor Agent systems from critical infrastructure
- Deploy host-based intrusion detection systems (HIDS) to monitor for suspicious command execution patterns
🔍 How to Verify
Check if Vulnerable:
Check if Opsview Monitor Agent version is 6.8.x and if NRPE service is running on port 5666. Use nmap scan: nmap -p 5666 --script nrpe-enum <target_ip>Check Version:
opsview-agent --versionVerify Fix Applied:
Verify agent version is 6.8.2 or later using: opsview-agent --version. Test NRPE service response to crafted requests using proof-of-concept tools.📡 Detection & Monitoring
Log Indicators:
- Unusual NRPE plugin execution in Opsview logs
- Suspicious command execution events in Windows Event Logs (Event ID 4688)
- Multiple failed NRPE authentication attempts
Network Indicators:
- Unusual traffic to port 5666 from non-management systems
- NRPE requests containing command control characters or shell metacharacters
SIEM Query:
source="opsview.log" AND "NRPE" AND ("command injection" OR "shell metacharacter" OR suspicious_command_pattern)