An issue was discovered on Sigma Design Z-Wave S0 through S2 devices.

Summary

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.