CVE-2025-27395
📋 TL;DR
This vulnerability in Siemens SCALANCE LPE9403 industrial routers allows authenticated high-privilege attackers to read and write arbitrary files via SFTP. It affects all versions before V4.0 of the 6GK5998-3GS00-2AC2 model. This improper access control could lead to system compromise.
💻 Affected Systems
- Siemens SCALANCE LPE9403 (6GK5998-3GS00-2AC2)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover, configuration manipulation, credential theft, or firmware modification leading to persistent backdoors in industrial networks.
Likely Case
Unauthorized access to sensitive configuration files, log tampering, or installation of malicious scripts on affected devices.
If Mitigated
Limited impact if proper network segmentation, least privilege access, and monitoring are implemented.
🎯 Exploit Status
Exploitation requires authenticated high-privilege access; no public exploit code known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: V4.0 or later
Vendor Advisory: https://cert-portal.siemens.com/productcert/html/ssa-075201.html
Restart Required: No
Instructions:
1. Download firmware V4.0 or later from Siemens Industrial Security. 2. Backup current configuration. 3. Upload new firmware via web interface or CLI. 4. Verify successful update.
🔧 Temporary Workarounds
Restrict SFTP Access
allDisable SFTP service if not required, or restrict access to specific trusted IP addresses only.
Implement Least Privilege
allReview and reduce user privileges to minimum required for operations; remove unnecessary high-privilege accounts.
🧯 If You Can't Patch
- Network segmentation: Isolate SCALANCE devices in separate VLANs with strict firewall rules.
- Enhanced monitoring: Implement file integrity monitoring and alert on unusual SFTP activity.
🔍 How to Verify
Check if Vulnerable:
Check device firmware version via web interface (System > Device Information) or CLI 'show version' command.Check Version:
show versionVerify Fix Applied:
Confirm firmware version is V4.0 or higher and test SFTP access with limited privilege accounts.📡 Detection & Monitoring
Log Indicators:
- Unusual SFTP connections from unexpected sources
- Multiple failed SFTP authentication attempts
- File access/modification patterns outside normal operations
Network Indicators:
- SFTP traffic to SCALANCE devices from unauthorized IPs
- Unusual file transfer sizes or frequencies
SIEM Query:
source="scalance_logs" AND (event="SFTP_ACCESS" OR event="FILE_MODIFY") AND user="admin"