CVE-2021-22738
📋 TL;DR
This vulnerability in Schneider Electric homeLYnk and spaceLYnk systems allows attackers to brute-force credentials due to weak cryptographic algorithms. Affected systems running version 2.60 and earlier could have their authentication bypassed, leading to unauthorized access to building automation controls.
💻 Affected Systems
- homeLYnk (Wiser For KNX)
- spaceLYnk
📦 What is this software?
Homelynk Firmware by Schneider Electric
Spacelynk Firmware by Schneider Electric
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of building automation systems allowing attackers to manipulate HVAC, lighting, security systems, and potentially cause physical damage or safety hazards.
Likely Case
Unauthorized access to building management interfaces enabling surveillance, data theft, or disruption of building operations.
If Mitigated
Limited impact with strong network segmentation, monitoring, and credential rotation practices in place.
🎯 Exploit Status
Exploitation requires network access to the device but uses standard brute-force techniques against weak cryptography.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after V2.60
Vendor Advisory: https://download.schneider-electric.com/files?p_Doc_Ref=SEVD-2021-130-04
Restart Required: Yes
Instructions:
1. Download updated firmware from Schneider Electric portal. 2. Backup current configuration. 3. Apply firmware update via web interface. 4. Verify successful update and restore configuration if needed.
🔧 Temporary Workarounds
Network Segmentation
allIsolate building automation systems from general network and internet access
Access Control Lists
allImplement strict firewall rules limiting access to management interfaces
🧯 If You Can't Patch
- Implement network-level brute force protection (fail2ban, rate limiting)
- Enable multi-factor authentication if supported, otherwise enforce complex password policies
🔍 How to Verify
Check if Vulnerable:
Check firmware version in web interface: System > About or similar menuCheck Version:
N/A - Check via web interface onlyVerify Fix Applied:
Confirm firmware version is greater than V2.60 in system information📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts from single IP
- Successful logins from unusual locations/times
Network Indicators:
- High volume of authentication requests to management ports
- Traffic patterns consistent with brute force tools
SIEM Query:
sourceIP="*" destinationPort=80 OR destinationPort=443 action="AUTH_FAILED" count>10 within 5m