CVE-2021-40520
📋 TL;DR
Airangel HSMX Gateway devices through version 5.2.04 use weak SSH credentials, allowing attackers to easily guess or brute-force access. This affects all deployments of these gateway devices with default or weak SSH configurations. Attackers can gain administrative access to the gateway.
💻 Affected Systems
- Airangel HSMX Gateway
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full compromise of the HSMX Gateway leading to network pivoting, data exfiltration, or disruption of connected systems.
Likely Case
Unauthorized administrative access to the gateway device, enabling configuration changes, credential harvesting, or service disruption.
If Mitigated
Limited impact due to strong authentication controls, network segmentation, and monitoring.
🎯 Exploit Status
Exploitation involves SSH brute-forcing or credential guessing; no complex exploit code needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://airangel.com/hsmx-gateway/
Restart Required: No
Instructions:
No official patch identified; follow workarounds and contact vendor for updates.
🔧 Temporary Workarounds
Change SSH Credentials
linuxReplace default or weak SSH passwords with strong, unique credentials.
passwd
ssh-keygen -t rsa -b 4096
Disable SSH if Unused
linuxTurn off SSH service if remote administration is not required.
systemctl stop ssh
systemctl disable ssh
🧯 If You Can't Patch
- Implement network segmentation to isolate HSMX Gateway from untrusted networks.
- Enable SSH key-based authentication and disable password authentication.
🔍 How to Verify
Check if Vulnerable:
Check if SSH is enabled and uses weak/default credentials via manual testing or scanning.Check Version:
Check device firmware version via web interface or CLI; specific command unknown.Verify Fix Applied:
Verify SSH uses strong passwords or key-based auth, and test brute-force resistance.📡 Detection & Monitoring
Log Indicators:
- Failed SSH login attempts from multiple IPs
- Successful SSH logins from unusual sources
Network Indicators:
- SSH brute-force traffic patterns to gateway IP
SIEM Query:
source="ssh" AND (event="Failed password" OR event="Accepted password") AND dest_ip="HSMX_GATEWAY_IP"