Siemens SIMATIC S7-1500 CPU Denial of Service
Act NowICS-CERT ICSA-14-226-01May 17, 2014
Summary
The Siemens SIMATIC S7-1500 CPU contains a denial of service vulnerability caused by missing input validation (CWE-306). An unauthenticated remote attacker can send specially crafted packets to the device over the S7 protocol, causing it to become unresponsive and cease operations. No software patch is available from Siemens for devices running firmware below version 1.6.
What this means
What could happen
An unauthenticated attacker on your network could send crafted packets to the S7-1500 PLC, causing it to become unresponsive and halt production processes until the device is manually restarted.
Who's at risk
Water authorities, municipal utilities, and any facility operating Siemens S7-1500 programmable logic controllers in production processes should be concerned. This affects industrial automation environments where the S7-1500 controls critical process operations such as water treatment, pumping, or electrical distribution.
How it could be exploited
An attacker with network access to port 102 (Siemens S7 protocol) on the S7-1500 CPU can send specially crafted packets that trigger a denial of service condition, causing the PLC to stop responding to legitimate control requests and halt its execution of production logic.
Prerequisites
- Network access to port 102 (Siemens S7 protocol)
- No authentication required
remotely exploitableno authentication requiredno patch availableaffects safety-critical systems
Exploitability
High exploit probability (EPSS 13.7%)
Affected products (1)
ProductAffected VersionsFix Status
SIMATIC S7-1500 CPU: <V1.6<V1.6No fix (EOL)
Remediation & Mitigation
0/4
Do now
0/1WORKAROUNDRestrict network access to port 102 on the S7-1500 CPU using a firewall or network ACL to allow only authorized engineering workstations and SCADA servers
Mitigations - no patch available
0/3SIMATIC S7-1500 CPU: <V1.6 has reached End of Life. The vendor will not release a patch. Apply the following compensating controls:
HARDENINGImplement network segmentation to isolate the S7-1500 CPU on a restricted OT network with controlled ingress/egress filtering
HARDENINGMonitor network traffic to the S7-1500 for unusual connection attempts or malformed S7 protocol packets
HARDENINGEstablish a routine to manually verify S7-1500 CPU operational status and implement automated alerts for loss of connectivity
CVEs (1)
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