CVE-2020-25241
📋 TL;DR
This vulnerability in Siemens SIMATIC MV400 industrial cameras allows attackers to terminate arbitrary TCP sessions by sending specially crafted TCP RST packets with invalid sequence numbers. This affects all SIMATIC MV400 family devices running versions before V7.0.6, potentially disrupting industrial control system communications.
💻 Affected Systems
- SIMATIC MV400 family industrial cameras
📦 What is this software?
Simatic Mv420 Sr B Body Firmware by Siemens
Simatic Mv420 Sr P Body Firmware by Siemens
⚠️ Risk & Real-World Impact
Worst Case
Complete disruption of industrial control system communications leading to production downtime, safety system failures, or loss of process visibility in critical infrastructure.
Likely Case
Intermittent network connection drops causing communication failures between cameras and control systems, disrupting monitoring and automation functions.
If Mitigated
Minimal impact with proper network segmentation and monitoring, though some service disruption may still occur during attacks.
🎯 Exploit Status
Exploitation requires network access to the device but no authentication. Attackers need to craft TCP RST packets with invalid sequence numbers, which is straightforward with common network tools.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: V7.0.6
Vendor Advisory: https://cert-portal.siemens.com/productcert/pdf/ssa-599268.pdf
Restart Required: Yes
Instructions:
1. Download firmware V7.0.6 from Siemens support portal. 2. Backup current configuration. 3. Upload new firmware via web interface or TIA Portal. 4. Reboot device. 5. Verify firmware version is V7.0.6 or higher.
🔧 Temporary Workarounds
Network Segmentation
allIsolate SIMATIC MV400 devices in separate VLANs with strict firewall rules to limit TCP RST packet exposure.
Rate Limiting
allConfigure network devices to limit TCP RST packets to industrial networks.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected cameras from untrusted networks
- Deploy intrusion detection systems to monitor for TCP RST flooding and alert on suspicious patterns
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface (System > About) or TIA Portal. If version is below V7.0.6, device is vulnerable.Check Version:
No CLI command - check via web interface at http://<device-ip>/system/about or using Siemens TIA Portal software.Verify Fix Applied:
Confirm firmware version is V7.0.6 or higher in device web interface. Test TCP session stability under normal operating conditions.📡 Detection & Monitoring
Log Indicators:
- Unexpected TCP connection resets
- Increased TCP RST packets in network logs
- Camera communication failures in industrial control system logs
Network Indicators:
- Spike in TCP RST packets to industrial camera IPs
- TCP packets with invalid sequence numbers
- Abnormal TCP session terminations
SIEM Query:
source_ip=* AND dest_ip=<camera_ip> AND tcp.flags.reset=1 AND count>threshold