CVE-2021-44080
📋 TL;DR
This vulnerability allows authenticated administrators on SerComm h500s devices to execute arbitrary operating system commands as root via command injection in the setup.cgi endpoint. It affects SerComm h500s devices running firmware version lowi-h500s-v3.4.22. Attackers with administrative credentials can achieve complete system compromise.
💻 Affected Systems
- SerComm h500s
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device takeover, installation of persistent backdoors, lateral movement to other network devices, data exfiltration, and use as a pivot point for further attacks.
Likely Case
Unauthorized administrative access leading to device configuration changes, credential harvesting, and potential network reconnaissance.
If Mitigated
Limited impact if strong authentication controls, network segmentation, and proper access controls are implemented.
🎯 Exploit Status
Exploitation requires administrative credentials. The vulnerability is in the connection_type parameter of the statussupport_diagnostic_tracing.json endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check with SerComm for updated firmware
Vendor Advisory: https://www.sercomm.com
Restart Required: Yes
Instructions:
1. Check SerComm website for firmware updates. 2. Download appropriate firmware for h500s model. 3. Upload firmware via web interface. 4. Apply update and restart device.
🔧 Temporary Workarounds
Restrict Administrative Access
linuxLimit administrative access to trusted IP addresses only
iptables -A INPUT -p tcp --dport 80 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Disable Diagnostic Tracing Endpoint
linuxBlock access to the vulnerable endpoint if not needed
iptables -A INPUT -p tcp --dport 80 -m string --string "statussupport_diagnostic_tracing.json" --algo bm -j DROP
🧯 If You Can't Patch
- Isolate device in separate VLAN with strict firewall rules
- Implement multi-factor authentication for administrative access
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface or SSH: cat /etc/version | grep h500sCheck Version:
cat /etc/versionVerify Fix Applied:
Verify firmware version is updated beyond lowi-h500s-v3.4.22📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cgi-bin/setup.cgi with connection_type parameter
- Suspicious command execution patterns in system logs
- Multiple failed authentication attempts followed by successful login
Network Indicators:
- Unusual outbound connections from device
- Traffic to suspicious IP addresses
- Unexpected SSH or telnet sessions originating from device
SIEM Query:
source="httpd" AND uri="/cgi-bin/setup.cgi" AND (connection_type="*;*" OR connection_type="*|*" OR connection_type="*`*" OR connection_type="*$(*)")🔗 References
- https://research.nccgroup.com/2022/05/24/technical-advisory-sercomm-h500s-authenticated-remote-command-execution-cve-2021-44080/
- https://www.sercomm.com
- https://research.nccgroup.com/2022/05/24/technical-advisory-sercomm-h500s-authenticated-remote-command-execution-cve-2021-44080/
- https://www.sercomm.com
