CVE-2023-6640 in PC Controller
Summary
by MITRE • 02/21/2024
Malformed S2 Nonce Get Command Class packets can be sent to crash PC Controller v5.54.0 and earlier.
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Analysis
by VulDB Data Team • 02/13/2025
The vulnerability identified as CVE-2023-6640 represents a critical denial of service condition affecting PC Controller software versions 5.54.0 and earlier. This flaw specifically targets the Secure S2 (S2) protocol implementation within the Z-Wave communication framework, where malformed S2 Nonce Get Command Class packets can trigger system instability and complete service disruption. The vulnerability exists within the packet processing logic of the Z-Wave controller software, where insufficient input validation allows specially crafted malformed data to cause unexpected behavior in the receiving system.
The technical root cause of this vulnerability lies in the improper handling of Command Class packets within the S2 security layer of Z-Wave protocol implementation. When the PC Controller receives a malformed S2 Nonce Get packet, the software fails to properly validate the packet structure and content before processing. This validation gap creates an execution path where the controller attempts to parse malformed data without proper bounds checking or error handling mechanisms. The flaw manifests as a buffer overflow condition or invalid memory access pattern that leads to immediate system crash and termination of the controller service. This type of vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-129, which covers validation of input boundaries.
The operational impact of CVE-2023-6640 extends beyond simple service disruption to potentially compromise entire Z-Wave network security infrastructure. When a PC Controller crashes due to this vulnerability, it can affect all connected Z-Wave devices that rely on that controller for network management and communication. This creates cascading failures where legitimate network traffic becomes disrupted and security features may be temporarily disabled. The vulnerability is particularly concerning in industrial or commercial settings where Z-Wave controllers manage critical infrastructure automation systems, as the crash could lead to unauthorized access attempts or complete network isolation. From an attack perspective, this vulnerability maps to ATT&CK technique T1499.004, which covers network disruption attacks through service availability compromises.
Mitigation strategies for this vulnerability require immediate software updates to PC Controller versions that address the malformed packet handling issue. Organizations should implement network segmentation to isolate Z-Wave controllers from critical systems and establish monitoring for unusual packet patterns that might indicate exploitation attempts. The recommended approach includes deploying firmware updates that introduce proper input validation for S2 Command Class packets and implementing rate limiting mechanisms to prevent abuse of the vulnerability. Additionally, network administrators should consider implementing intrusion detection systems that can identify and alert on malformed S2 packets before they reach vulnerable controllers. The vulnerability demonstrates the importance of robust input validation in security-critical systems and highlights the need for comprehensive testing of protocol implementations against malformed data scenarios. Organizations should also consider implementing redundant controller systems to maintain network availability during patch deployment windows and establish incident response procedures specifically addressing Z-Wave protocol vulnerabilities.