CVE-2021-44693 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 • 12/13/2022
This vulnerability affects a wide range of Siemens industrial automation and control systems including drive controllers, open controllers, cpu families, and simulation software. The flaw manifests in devices that fail to properly handle specially crafted packets sent to port 102/tcp which is the standard port for iso-tsap communication in industrial protocols. This represents a critical weakness in the protocol handling layer of these systems, where malformed packet processing can lead to system instability. The vulnerability impacts multiple product lines including SIMATIC Drive Controller family, ET 200SP Open Controller, S7-1200 CPU family, S7-1500 CPU family, S7-PLCSIM Advanced, and various TIM modules. These devices operate in critical industrial environments where reliability and continuous operation are paramount, making any denial-of-service condition potentially catastrophic. The vulnerability is particularly concerning as it affects all versions of these products except those explicitly mentioned as patched, indicating a widespread exposure across the industrial control system landscape.
The technical root cause involves improper input validation and packet processing within the communication stack of affected Siemens devices. When these systems receive specially crafted packets on port 102/tcp, the parsing logic fails to properly handle the malformed data structure, leading to system resource exhaustion or unexpected behavior that results in service disruption. This type of vulnerability typically falls under CWE-129 Input Validation and CWE-476 NULL Pointer Dereference categories, representing a classic buffer overflow or input sanitization failure. The attack vector is network-based requiring only that an attacker can send packets to the target device's port 102, which is commonly exposed in industrial networks. The vulnerability is classified as a denial-of-service condition because it allows an attacker to disrupt the normal operation of industrial control systems without necessarily gaining unauthorized access or executing malicious code.
The operational impact of this vulnerability extends beyond simple service interruption as these devices typically control critical industrial processes including manufacturing operations, process control, and automation systems. When industrial control systems become unavailable due to denial-of-service attacks, production lines can halt, safety systems may fail, and operational continuity can be severely compromised. The attack requires minimal technical expertise to execute, making it particularly dangerous as it can be exploited by threat actors with basic network knowledge. The affected systems are often deployed in environments where network segmentation is insufficient or where industrial networks are directly connected to corporate networks, increasing the attack surface. This vulnerability directly impacts the availability aspect of the CIA triad and can be categorized under ATT&CK technique T1499.002 for Network Denial of Service, potentially leading to operational technology (OT) system failures that could have physical consequences.
Organizations should immediately implement network segmentation to isolate affected industrial control systems from general corporate networks, particularly blocking inbound traffic to port 102/tcp on devices that cannot be immediately patched. The recommended mitigation strategy involves applying the vendor-supplied patches and updates for all affected product versions, with particular attention to the specific version requirements mentioned in the vulnerability description. Network monitoring should be enhanced to detect unusual packet patterns targeting port 102, and baseline network behavior should be established to identify potential exploitation attempts. Device administrators should also consider implementing access control lists and firewall rules to limit which systems can communicate with affected devices on their industrial networks. The vulnerability highlights the need for robust industrial cybersecurity practices including regular vulnerability assessments, network monitoring, and incident response planning specifically tailored for operational technology environments. Organizations should also review their industrial control system security postures and consider implementing additional layers of defense including network intrusion detection systems and industrial protocol monitoring solutions to detect and prevent similar attacks.