CVE-2017-9945 in 7KM PAC Switched Ethernet PROFINET Expansion Module
Summary
by MITRE
In the Siemens 7KM PAC Switched Ethernet PROFINET expansion module (All versions < V2.1.3), a Denial-of-Service condition could be induced by a specially crafted PROFINET DCP packet sent as a local Ethernet (Layer 2) broadcast. The affected component requires a manual restart via the main device to recover.
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Analysis
by VulDB Data Team • 12/27/2022
The Siemens 7KM PAC Switched Ethernet PROFINET expansion module represents a critical component within industrial automation environments where reliable network communication is paramount for operational continuity. This vulnerability affects all versions prior to V2.1.3 and demonstrates a significant weakness in the device's handling of PROFINET DCP (Device Configuration Protocol) packets. The issue manifests as a denial-of-service condition that can be triggered through carefully constructed network traffic, specifically targeting the Layer 2 broadcast mechanism that forms the foundation of PROFINET's device discovery and configuration processes. The vulnerability operates at the network protocol level, exploiting inherent weaknesses in how the device processes incoming configuration messages that are normally benign and essential for system operation.
The technical flaw lies in the insufficient validation and error handling mechanisms within the PROFINET DCP packet processing subsystem of the affected module. When a specially crafted malicious packet is transmitted as a local Ethernet broadcast, the device fails to properly sanitize or reject malformed input data, causing the system to enter an unstable state that renders it unresponsive to normal network operations. This condition represents a classic buffer overflow or input validation vulnerability where the device's processing logic does not adequately check packet integrity before attempting to parse and act upon the received data. The vulnerability is particularly concerning because it operates at the data link layer, making it difficult to detect through traditional network monitoring tools and allowing attackers to exploit it without requiring elevated privileges or network access beyond what is normally permitted.
The operational impact of this vulnerability extends far beyond simple network disruption, potentially affecting entire industrial control systems that depend on continuous communication between devices and controllers. When the affected module becomes unresponsive, it can cause cascading failures throughout the PROFINET network, disrupting critical automation processes and potentially leading to production downtime or safety hazards in industrial environments. The requirement for manual restart via the main device represents a significant operational burden, as it may necessitate on-site intervention during critical production periods, potentially causing extended downtime and requiring specialized technical personnel. This vulnerability directly impacts the availability and reliability of industrial control systems, undermining the core principles of industrial cybersecurity and operational technology infrastructure resilience.
Organizations should implement immediate mitigations including network segmentation to isolate affected devices from general network traffic, deployment of network access control lists to filter malicious broadcast packets, and regular firmware updates to patch the vulnerability. The remediation process requires careful planning due to the operational criticality of industrial environments and may involve coordinated downtime scheduling to ensure minimal impact on production operations. Security controls should also include monitoring for unusual broadcast traffic patterns that may indicate exploitation attempts, as well as implementing network intrusion detection systems specifically configured to identify PROFINET DCP protocol anomalies. This vulnerability aligns with CWE-121 and CWE-122 categories related to buffer overflow conditions and improper input validation, while also mapping to ATT&CK techniques involving network denial of service and operational technology system disruption. The incident highlights the importance of maintaining up-to-date security patches in industrial environments and demonstrates the critical need for robust security controls in operational technology infrastructure to prevent exploitation of vulnerabilities that could compromise industrial safety and production continuity.