CVE-2021-37182
📋 TL;DR
This vulnerability affects Siemens SCALANCE industrial network switches with OSPF enabled. An unauthenticated remote attacker can send specially crafted OSPF packets to cause network interruptions by exploiting improper validation of checksum and length fields in OSPF LS Update messages.
💻 Affected Systems
- SCALANCE XM408-4C
- SCALANCE XM408-4C (L3 int.)
- SCALANCE XM408-8C
- SCALANCE XM408-8C (L3 int.)
- SCALANCE XM416-4C
- SCALANCE XM416-4C (L3 int.)
- SCALANCE XR524-8C, 1x230V
- SCALANCE XR524-8C, 1x230V (L3 int.)
- SCALANCE XR524-8C, 24V
- SCALANCE XR524-8C, 24V (L3 int.)
- SCALANCE XR524-8C, 2x230V
- SCALANCE XR524-8C, 2x230V (L3 int.)
- SCALANCE XR526-8C, 1x230V
- SCALANCE XR526-8C, 1x230V (L3 int.)
- SCALANCE XR526-8C, 24V
- SCALANCE XR526-8C, 24V (L3 int.)
- SCALANCE XR526-8C, 2x230V
- SCALANCE XR526-8C, 2x230V (L3 int.)
- SCALANCE XR528-6M
- SCALANCE XR528-6M (2HR2)
- SCALANCE XR528-6M (2HR2, L3 int.)
- SCALANCE XR528-6M (L3 int.)
- SCALANCE XR552-12M
- SCALANCE XR552-12M (2HR2)
- SCALANCE XR552-12M (2HR2, L3 int.)
📦 What is this software?
Scalance Xr528 6m 2hr2 Firmware by Siemens
Scalance Xr528 6m 2hr2 L3 Firmware by Siemens
View all CVEs affecting Scalance Xr528 6m 2hr2 L3 Firmware →
Scalance Xr552 12m 2hr2 Firmware by Siemens
⚠️ Risk & Real-World Impact
Worst Case
Network-wide disruption causing denial of service in industrial environments, potentially affecting critical operations and production systems.
Likely Case
Localized network instability and routing disruptions affecting connected devices and systems.
If Mitigated
Minimal impact if OSPF is disabled or devices are properly segmented from untrusted networks.
🎯 Exploit Status
Exploitation requires OSPF to be enabled and network access to OSPF interfaces. No authentication is required to send OSPF packets.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: V6.5 or later
Vendor Advisory: https://cert-portal.siemens.com/productcert/pdf/ssa-145224.pdf
Restart Required: Yes
Instructions:
1. Download firmware version V6.5 or later from Siemens support portal. 2. Backup current configuration. 3. Upload new firmware via web interface or CLI. 4. Reboot device to apply update. 5. Verify firmware version after reboot.
🔧 Temporary Workarounds
Disable OSPF Protocol
allIf OSPF is not required for network operations, disable it to eliminate the vulnerability.
configure terminal
no router ospf
end
write memory
Network Segmentation
allRestrict access to OSPF interfaces using firewall rules or network segmentation to prevent unauthorized access.
🧯 If You Can't Patch
- Disable OSPF protocol on all affected devices if not required for network operations.
- Implement strict network segmentation and firewall rules to restrict access to OSPF interfaces from untrusted networks.
🔍 How to Verify
Check if Vulnerable:
Check device firmware version via web interface or CLI. If version is below V6.5 and OSPF is enabled, device is vulnerable.Check Version:
show versionVerify Fix Applied:
After patching, verify firmware version is V6.5 or later and OSPF functionality is working correctly.📡 Detection & Monitoring
Log Indicators:
- Unusual OSPF packet activity
- OSPF protocol errors or resets
- Network instability events
Network Indicators:
- Malformed OSPF packets with invalid checksums or length fields
- Unusual OSPF traffic patterns
SIEM Query:
source="industrial_switches" AND (event_type="ospf_error" OR protocol="ospf" AND packet_size>normal)