CVE-2020-9060 in Z-Wave
Summary
by MITRE • 01/10/2022
Z-Wave devices based on Silicon Labs 500 series chipsets using S2, including but likely not limited to the ZooZ ZST10 version 6.04, ZooZ ZEN20 version 5.03, ZooZ ZEN25 version 5.03, Aeon Labs ZW090-A version 3.95, and Fibaro FGWPB-111 version 4.3, are susceptible to denial of service and resource exhaustion via malformed SECURITY NONCE GET, SECURITY NONCE GET 2, NO OPERATION, or NIF REQUEST messages.
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Analysis
by VulDB Data Team • 01/12/2022
The vulnerability CVE-2020-9060 affects Z-Wave devices utilizing Silicon Labs 500 series chipsets with S2 security protocol implementation, creating a critical denial of service condition that can exhaust system resources through malformed message handling. This vulnerability specifically targets devices that process SECURITY NONCE GET, SECURITY NONCE GET 2, NO OPERATION, and NIF REQUEST messages, which are fundamental components of the Z-Wave network protocol stack. The affected devices include various smart home products from manufacturers such as ZooZ and Aeon Labs, highlighting the widespread nature of this security flaw across commercial Z-Wave implementations. The vulnerability stems from insufficient input validation and error handling mechanisms within the S2 security framework, which fails to properly process malformed packets that could trigger resource exhaustion conditions.
The technical flaw manifests when these devices receive specially crafted malicious messages that exploit buffer handling inconsistencies in the Z-Wave stack implementation. The vulnerability operates at the network protocol level, specifically targeting the security negotiation and message processing routines that are essential for establishing secure communication between Z-Wave devices. When processing malformed SECURITY NONCE GET or related messages, the affected chipsets fail to properly validate message structures and lengths, leading to memory corruption or excessive resource consumption. This behavior aligns with CWE-129, which describes improper validation of length of data, and CWE-772, which covers missing release of resource after effective lifetime, as the devices do not properly handle invalid message parameters that could cause memory exhaustion or system instability.
The operational impact of this vulnerability extends beyond simple denial of service, as it can render entire Z-Wave networks inoperable and compromise the security of connected smart home ecosystems. Attackers can exploit this vulnerability remotely through the Z-Wave network protocol, potentially causing widespread disruption to home automation systems that rely on these devices for security and convenience functions. The resource exhaustion aspect means that affected devices may become unresponsive, requiring manual intervention or power cycling to restore functionality, which creates operational challenges for users who depend on continuous network availability. This vulnerability particularly affects the ATT&CK technique T1489, which covers service stoppage, as the compromised devices can be rendered non-functional through controlled message injection attacks.
Mitigation strategies for this vulnerability should include firmware updates from device manufacturers, which typically address the underlying buffer handling and input validation issues in the Z-Wave stack implementation. Network segmentation and monitoring of Z-Wave traffic can help detect anomalous message patterns that may indicate exploitation attempts. Device administrators should implement regular firmware update schedules and maintain inventory of all Z-Wave devices to ensure comprehensive coverage of vulnerable components. The vulnerability demonstrates the importance of proper protocol implementation and input validation in embedded security systems, as it highlights how seemingly minor flaws in message handling can lead to significant operational disruptions and security compromise. Organizations should also consider implementing network access controls to limit exposure of Z-Wave networks to untrusted sources and maintain detailed logging of network activity to detect potential exploitation attempts.