CVE-2018-4834
📋 TL;DR
This vulnerability allows remote attackers to upload unauthorized firmware to Siemens Desigo building automation controllers without authentication. It affects multiple Desigo PXC and PXM series controllers with web modules enabled. Attackers with network access can completely compromise device functionality.
💻 Affected Systems
- Siemens Desigo PXC00-E.D
- Desigo PXC00/64/128-U
- Desigo PXC001-E.D
- Desigo PXC100-E.D
- Desigo PXC12-E.D
- Desigo PXC200-E.D
- Desigo PXC22-E.D
- Desigo PXC22.1-E.D
- Desigo PXC36.1-E.D
- Desigo PXC50-E.D
- Desigo PXM20-E
📦 What is this software?
Pxc00\/50\/100\/200 E.d Firmware by Siemens
⚠️ Risk & Real-World Impact
Worst Case
Complete device takeover with malicious firmware installation leading to building system disruption, data theft, or physical safety risks in critical infrastructure.
Likely Case
Unauthorized firmware modification enabling persistent backdoors, data exfiltration, or disruption of building automation systems.
If Mitigated
Limited to internal network attacks if proper segmentation and access controls are implemented.
🎯 Exploit Status
Authentication bypass makes exploitation straightforward for attackers with network access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: V4.10.111, V5.0.171, V5.10.69, V6.0.204 or later
Vendor Advisory: https://cert-portal.siemens.com/productcert/pdf/ssa-824231.pdf
Restart Required: Yes
Instructions:
1. Download appropriate firmware update from Siemens support portal. 2. Backup current configuration. 3. Apply firmware update following Siemens documentation. 4. Verify successful update and restore configuration if needed.
🔧 Temporary Workarounds
Disable Web Module
allDisable web interface on affected PXC00/64/128-U models to prevent remote exploitation.
Configure via Desigo CC or local interface to disable web module
Network Segmentation
allIsolate Desigo controllers in separate VLAN with strict firewall rules.
Configure firewall to block all inbound traffic to Desigo controllers except from management stations
🧯 If You Can't Patch
- Implement strict network segmentation with firewall rules blocking all unnecessary access
- Disable web modules where possible and use local interfaces only
🔍 How to Verify
Check if Vulnerable:
Check firmware version via Desigo CC interface or local display. Compare against patched versions.Check Version:
Use Desigo CC or access controller web interface to view firmware versionVerify Fix Applied:
Confirm firmware version shows V4.10.111, V5.0.171, V5.10.69, V6.0.204 or later.📡 Detection & Monitoring
Log Indicators:
- Unauthorized firmware upload attempts
- Unexpected firmware version changes
- Authentication bypass attempts
Network Indicators:
- HTTP POST requests to firmware upload endpoints without authentication
- Unusual traffic to controller web interfaces
SIEM Query:
source_ip=* dest_ip=desigo_controller (http_method=POST AND uri_contains="firmware") AND NOT user_authenticated=true