CVE-2019-6839
📋 TL;DR
This vulnerability allows low-privileged users to upload malicious files to Schneider Electric's U.motion KNX servers. Attackers could potentially execute arbitrary code, compromise the building automation system, or gain persistent access. Affected systems include specific U.motion KNX Server models and Touch interfaces.
💻 Affected Systems
- MEG6501-0001 - U.motion KNX server
- MEG6501-0002 - U.motion KNX Server Plus
- MEG6260-0410 - U.motion KNX Server Plus, Touch 10
- MEG6260-0415 - U.motion KNX Server Plus, Touch 15
📦 What is this software?
Meg6260 0410 Firmware by Schneider Electric
Meg6260 0415 Firmware by Schneider Electric
Meg6501 0001 Firmware by Schneider Electric
Meg6501 0002 Firmware by Schneider Electric
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, lateral movement within building automation networks, and physical safety risks if environmental controls are manipulated.
Likely Case
Unauthorized file upload leading to web shell deployment, data exfiltration, or denial of service affecting building automation functions.
If Mitigated
Limited impact if proper network segmentation, file upload restrictions, and privilege separation are implemented.
🎯 Exploit Status
Exploitation requires low-privileged credentials but is straightforward once access is obtained. No public exploit code is known, but the vulnerability type is commonly weaponized.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to Schneider Electric advisory SEVD-2019-253-01 for specific patched versions
Vendor Advisory: https://www.se.com/ww/en/download/document/SEVD-2019-253-01/
Restart Required: Yes
Instructions:
1. Download the firmware update from Schneider Electric's website
2. Backup current configuration
3. Apply the firmware update following vendor instructions
4. Restart the U.motion server
5. Verify the update was successful
🔧 Temporary Workarounds
Restrict file upload permissions
allConfigure the U.motion server to restrict file uploads to administrative users only
Network segmentation
allIsolate U.motion servers from untrusted networks and implement strict firewall rules
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach the U.motion web interface
- Disable unnecessary file upload functionality if not required for operations
🔍 How to Verify
Check if Vulnerable:
Check firmware version against Schneider Electric's advisory. If version is older than patched version listed in SEVD-2019-253-01, system is vulnerable.Check Version:
Check version through U.motion web interface or consult system documentation for version checking procedureVerify Fix Applied:
Verify firmware version matches or exceeds the patched version specified in the vendor advisory.📡 Detection & Monitoring
Log Indicators:
- Unusual file upload activity from low-privileged accounts
- Unexpected file creation in server directories
- Authentication logs showing suspicious access patterns
Network Indicators:
- HTTP POST requests to file upload endpoints from unauthorized IPs
- Unusual outbound connections from U.motion servers
SIEM Query:
source="u.motion" AND (event_type="file_upload" OR http_method="POST") AND user_privilege="low"