CVE-2021-44694 in SIMATIC Drive Controller Family
Summary
by MITRE • 12/13/2022
A vulnerability has been identified in SIMATIC Drive Controller family (All versions < V3.0.1), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) (All versions), SIMATIC S7-1200 CPU family (incl. SIPLUS variants) (All versions < V4.6.0), SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions < V3.0.1), SIMATIC S7-1500 Software Controller (All versions), SIMATIC S7-PLCSIM Advanced (All versions < V5.0), SIPLUS TIM 1531 IRC (All versions), TIM 1531 IRC (All versions). Affected devices don't process correctly certain special crafted packets sent to port 102/tcp, which could allow an attacker to cause a denial-of-service in the device.
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Analysis
by VulDB Data Team • 01/08/2023
This vulnerability affects a broad range of Siemens industrial control systems including drive controllers, open controllers, cpu families, and simulation software. The flaw resides in the handling of specially crafted network packets sent to port 102/tcp which is the standard port for ISO-on-TCP protocol used in industrial communication. When these malformed packets are received, the affected devices fail to process them correctly and experience denial-of-service conditions. This represents a critical security weakness in industrial environments where continuous operation is essential for process control and automation systems.
The technical implementation of this vulnerability stems from inadequate input validation and error handling within the network protocol stack of these industrial devices. Port 102/tcp serves as the communication endpoint for ISO 8073 and ISO 9542 protocols which are fundamental to Siemens' industrial communication standards. The flaw manifests when devices receive packets that contain malformed data structures or unexpected control sequences that trigger unexpected behavior in the protocol parser. This type of vulnerability falls under CWE-129 Input Validation and Output Encoding, specifically related to improper handling of network protocol data structures. The vulnerability aligns with ATT&CK technique T1499.004 for Network Denial of Service, where adversaries exploit protocol implementation weaknesses to disrupt system availability.
The operational impact of this vulnerability extends beyond simple service interruption as it affects critical infrastructure components that form the backbone of industrial automation systems. When affected devices experience denial-of-service conditions, production processes may halt or become unstable, leading to significant financial losses and potential safety hazards. The affected systems include SIMATIC S7-1500 CPUs, S7-1200 CPUs, ET 200SP controllers, and various simulation environments that are commonly deployed in manufacturing, process control, and infrastructure management applications. These systems typically operate in closed-loop environments where availability is paramount, making the potential for disruption particularly severe in industrial settings.
Mitigation strategies for this vulnerability require immediate attention from industrial control system administrators and cybersecurity teams. The most effective approach involves applying the vendor-supplied patches and firmware updates that address the specific protocol handling issues in the affected devices. Organizations should also implement network segmentation and access controls to limit exposure of these devices to untrusted networks. Network monitoring should be enhanced to detect unusual traffic patterns on port 102/tcp that might indicate exploitation attempts. Additionally, implementing network intrusion detection systems specifically configured to identify malformed protocol packets can provide early warning of potential attacks. The vulnerability demonstrates the importance of maintaining up-to-date industrial control system firmware and implementing robust network security practices in operational technology environments where traditional cybersecurity measures may not be sufficient.