CVE-2019-19643 in Smart Connect KNX Vaillant
Summary
by MITRE
ise smart connect KNX Vaillant 1.2.839 contain a Denial of Service.
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Analysis
by VulDB Data Team • 08/14/2020
The CVE-2019-19643 vulnerability affects the ise smart connect KNX Vaillant device version 1.2.839, presenting a critical denial of service condition that can severely impact building automation systems. This vulnerability resides within the device's network communication handling mechanisms, specifically targeting its ability to process incoming requests and maintain operational continuity. The issue manifests when the device encounters malformed or specially crafted network packets that trigger unexpected behavior in the underlying software stack, ultimately leading to complete system unavailability.
The technical flaw stems from inadequate input validation and error handling within the KNX protocol implementation used by the ise smart connect device. When the device receives network traffic that does not conform to expected message formats or contains unexpected data sequences, the system fails to properly sanitize these inputs before processing. This lack of proper validation creates a condition where malicious actors or system malfunctions can trigger a cascade of failures that result in the device becoming unresponsive. The vulnerability operates at the network layer where the device processes KNX (Knx Network eXchange) protocol communications, making it particularly dangerous for building automation environments where continuous operation is critical.
The operational impact of this denial of service vulnerability extends far beyond simple device unavailability, particularly in commercial and industrial settings where building automation systems control heating, ventilation, air conditioning, lighting, and security functions. When the ise smart connect KNX Vaillant device becomes unresponsive, it can cause complete disruption to building climate control systems, potentially leading to uncomfortable conditions, increased energy consumption, and in severe cases, equipment damage due to lack of proper environmental regulation. The vulnerability affects not only individual device functionality but can also compromise the entire KNX network infrastructure that relies on proper communication between multiple devices.
Security researchers have classified this vulnerability under CWE-400, which addresses "Uncontrolled Resource Consumption," specifically related to denial of service conditions. The ATT&CK framework categorizes this as a system service disruption technique that can be leveraged by adversaries to gain operational advantages by making systems unavailable to legitimate users. The vulnerability's impact is amplified in environments where the device serves as a critical communication hub within larger building automation networks, as the failure of a single device can cascade through interconnected systems. Organizations should consider implementing network segmentation strategies and monitoring for unusual traffic patterns that might indicate exploitation attempts, while also ensuring timely firmware updates are deployed to address this known weakness in the device's communication protocols.
Mitigation strategies should include immediate firmware updates from the manufacturer when available, network access control implementations to restrict unauthorized communication with the device, and comprehensive monitoring of KNX network traffic for anomalous patterns that could indicate exploitation attempts. Additionally, organizations should implement redundant systems where possible and establish clear incident response procedures for handling device failures within their building automation infrastructure. The vulnerability highlights the importance of robust input validation and error handling in embedded systems, particularly those operating in critical infrastructure environments where reliability and availability are paramount requirements.