CVE-2022-24042
📋 TL;DR
This vulnerability allows attackers to reuse captured authentication tokens beyond their intended expiration time in Siemens Desigo building automation systems. Attackers can gain unauthorized access to system controls by exploiting non-expiring session tokens. Affected systems include Desigo DXR2, PXC3, PXC4, and PXC5 controllers with outdated firmware.
💻 Affected Systems
- Desigo DXR2
- Desigo PXC3
- Desigo PXC4
- Desigo PXC5
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to manipulate building controls (HVAC, lighting, security systems), cause physical damage, or disrupt critical operations.
Likely Case
Unauthorized access to building management systems leading to data theft, surveillance bypass, or manipulation of environmental controls.
If Mitigated
Limited impact if proper network segmentation and monitoring are in place, though token reuse could still enable lateral movement.
🎯 Exploit Status
Requires initial authentication token capture (via MITM, logs, or other means), then simple reuse of captured token.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: DXR2: V01.21.142.5-22, PXC3: V01.21.142.4-18, PXC4/PXC5: V02.20.142.10-10884
Vendor Advisory: https://cert-portal.siemens.com/productcert/pdf/ssa-626968.pdf
Restart Required: Yes
Instructions:
1. Download firmware update from Siemens support portal. 2. Backup current configuration. 3. Apply firmware update following vendor documentation. 4. Restart affected devices. 5. Verify token expiration is now enforced.
🔧 Temporary Workarounds
Network segmentation and access control
allRestrict access to Desigo web interfaces to authorized users only using firewall rules and network segmentation.
Session monitoring and forced logout
allImplement additional session monitoring and force manual logout after auto-logoff timeout periods.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Desigo controllers from general network traffic
- Deploy web application firewall (WAF) with session fixation protection and enforce shorter session timeouts
🔍 How to Verify
Check if Vulnerable:
Check firmware version via Desigo web interface or CLI. Compare against patched versions listed in affected_systems.versions.Check Version:
Check via Desigo web interface: System > About or via SSH: show versionVerify Fix Applied:
After patching, test token expiration by capturing a session token, waiting beyond auto-logoff timeout, and attempting to reuse it.📡 Detection & Monitoring
Log Indicators:
- Multiple successful logins from same token after timeout period
- Session tokens used beyond expected lifetime
- Unusual access patterns to building control endpoints
Network Indicators:
- Repeated authentication requests with same token
- Traffic to Desigo web interfaces from unexpected sources
SIEM Query:
source="desigo_web_logs" AND (event_type="auth_success" AND session_duration > 3600) OR (src_ip NOT IN allowed_ips AND dest_port=443)