CVE-2018-19983 in Z-Wave S0
Summary
by MITRE
An issue was discovered on Sigma Design Z-Wave S0 through S2 devices. An attacker first prepares a Z-Wave frame-transmission program (e.g., Z-Wave PC Controller, OpenZWave, CC1110, etc.). Next, the attacker conducts a DoS attack against the Z-Wave S0 Security version product by continuously sending divided "Nonce Get (0x98 0x81)" frames. The reason for dividing the "Nonce Get" frame is that, in security version S0, when a node receives a "Nonce Get" frame, the node produces a random new nonce and sends it to the Src node of the received "Nonce Get" frame. After the nonce value is generated and transmitted, the node transitions to wait mode. At this time, when "Nonce Get" is received again, the node discards the previous nonce value and generates a random nonce again. Therefore, because the frame is encrypted with previous nonce value, the received normal frame cannot be decrypted.
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Analysis
by VulDB Data Team • 04/19/2020
The vulnerability identified as CVE-2018-19983 affects Sigma Design Z-Wave S0 through S2 security devices, representing a significant denial of service weakness in wireless home automation protocols. This issue specifically targets the nonce management mechanism within Z-Wave security implementations, creating a condition where legitimate device communications can be disrupted through carefully crafted frame sequences. The vulnerability exploits fundamental security protocols designed to protect against replay attacks and ensure message integrity, ultimately undermining the reliability of Z-Wave networks. The attack vector involves sending fragmented "Nonce Get" frames with specific byte sequences 0x98 0x81, which triggers a cascade of security protocol failures that prevent normal device operations.
The technical flaw stems from improper state handling within Z-Wave security nodes when processing "Nonce Get" frames under S0 security version. When a node receives such a frame, it generates a new random nonce value and transmits it back to the source node, then transitions to a wait state for subsequent communications. However, the vulnerability occurs when an attacker sends multiple "Nonce Get" frames in rapid succession, causing the node to continuously discard previously generated nonces and generate new ones. This behavior creates a race condition where the node cannot properly maintain its security context, leading to decryption failures for legitimate frames that were encrypted using the discarded nonce values. The attack effectively consumes the node's processing resources while simultaneously breaking the cryptographic integrity of ongoing communications.
The operational impact of this vulnerability extends beyond simple service disruption to compromise the overall security posture of Z-Wave networks. Devices affected by this vulnerability become unable to process legitimate communications, creating a denial of service condition that can render entire home automation systems inoperable. The attack can be executed remotely without requiring physical access to the network, making it particularly concerning for residential and commercial installations. Additionally, the vulnerability affects multiple Z-Wave controller implementations including PC Controllers, OpenZWave, and CC1110 devices, indicating a widespread exposure across different hardware platforms and software implementations. This broad impact means that attackers can leverage various tools and platforms to execute the attack, increasing both the attack surface and the potential for successful exploitation.
Security professionals should consider this vulnerability in the context of CWE-362, which addresses concurrent execution using shared resources, and CWE-347, which covers improper verification of cryptographic signatures. The attack pattern aligns with ATT&CK technique T1499.004, which involves network disruption through resource exhaustion, and T1566.002, which encompasses spearphishing attacks through social engineering. The vulnerability demonstrates how cryptographic protocols can be subverted through protocol-level attacks rather than traditional exploitation methods, highlighting the importance of proper state management in security implementations. Organizations should implement network segmentation to isolate Z-Wave devices, deploy intrusion detection systems to monitor for anomalous frame patterns, and ensure firmware updates are applied promptly to address known vulnerabilities. The attack's simplicity and effectiveness underscore the critical need for robust security testing of wireless protocols and proper implementation of cryptographic state management.