Vulnerabilities > CVE-2018-19983 - Use of Insufficiently Random Values vulnerability in Silabs Z-Wave S0 Firmware and Z-Wave S2 Firmware
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.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| OS | 2 | |
| Hardware | 2 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Brute Force In this attack, some asset (information, functionality, identity, etc.) is protected by a finite secret value. The attacker attempts to gain access to this asset by using trial-and-error to exhaustively explore all the possible secret values in the hope of finding the secret (or a value that is functionally equivalent) that will unlock the asset. Examples of secrets can include, but are not limited to, passwords, encryption keys, database lookup keys, and initial values to one-way functions. The key factor in this attack is the attackers' ability to explore the possible secret space rapidly. This, in turn, is a function of the size of the secret space and the computational power the attacker is able to bring to bear on the problem. If the attacker has modest resources and the secret space is large, the challenge facing the attacker is intractable. While the defender cannot control the resources available to an attacker, they can control the size of the secret space. Creating a large secret space involves selecting one's secret from as large a field of equally likely alternative secrets as possible and ensuring that an attacker is unable to reduce the size of this field using available clues or cryptanalysis. Doing this is more difficult than it sounds since elimination of patterns (which, in turn, would provide an attacker clues that would help them reduce the space of potential secrets) is difficult to do using deterministic machines, such as computers. Assuming a finite secret space, a brute force attack will eventually succeed. The defender must rely on making sure that the time and resources necessary to do so will exceed the value of the information. For example, a secret space that will likely take hundreds of years to explore is likely safe from raw-brute force attacks.
- Signature Spoofing by Key Recreation An attacker obtains an authoritative or reputable signer's private signature key by exploiting a cryptographic weakness in the signature algorithm or pseudorandom number generation and then uses this key to forge signatures from the original signer to mislead a victim into performing actions that benefit the attacker.
- Session Credential Falsification through Prediction This attack targets predictable session ID in order to gain privileges. The attacker can predict the session ID used during a transaction to perform spoofing and session hijacking.