Severity: Unknown
Description: Z-Wave devices from Sierra Designs (circa 2013) and Silicon Labs (using S0 security) may use a known, shared network key of all zeros, allowing an attacker within radio range to spoof Z-Wave traffic.
CVSS Score: N/A
D
No data available.
No data available.
1. Risk Assessment
The vulnerability CVE-2013-20003 stems from the potential use of a shared, all-zeros network key in Z-Wave devices manufactured by Sierra Designs (circa 2013) and Silicon Labs (using S0 security). This allows an attacker within radio range to spoof Z-Wave traffic, effectively impersonating legitimate devices. The nature of the vulnerability is a weak cryptographic algorithm (CWE-327). The business impact can range from minor inconvenience to significant disruption, depending on the affected devices and their role. For example, compromised smart locks could allow unauthorized access, while control of smart lighting might simply be an annoyance. The likelihood of exploitation is moderate, as it requires an attacker to be within radio range of the Z-Wave network, but the ease of exploitation is relatively high once within range. The impact on confidentiality is limited, as the key primarily affects traffic integrity. The impact on integrity is high, as an attacker can send spoofed commands. Availability could be impacted if the attacker floods the network with spurious traffic or disables critical devices. The EPSS score of 0.001410000 indicates a relatively low, but not negligible, probability of exploitation.
2. Potential Attack Scenarios
An attacker could leverage this vulnerability to compromise a smart home automation system. The attack vector begins with the attacker positioning themselves within radio range of the Z-Wave network. The attacker can then utilize a software-defined radio (SDR) to capture Z-Wave traffic and observe the use of the all-zeros network key. Once confirmed, the attacker can spoof commands, such as unlocking a Z-Wave enabled smart lock. The attack process involves the attacker sending Z-Wave packets with a spoofed source address, leveraging the shared network key for authentication. The outcome is successful unauthorized access to the home. Another scenario involves an attacker repeatedly sending “off” commands to all Z-Wave controlled lights, causing a denial-of-service condition and disrupting normal operation. The attacker could also use the spoofed access to initiate a downgrade attack as described in the Pentest Partners blog, further weakening the security of the network.
3. Mitigation Recommendations
The primary mitigation is to update the firmware on affected Z-Wave devices to a version that uses a more robust network key. If a firmware update isn't available, consider replacing vulnerable devices with newer models that utilize more secure Z-Wave Plus or Z-Wave LR protocols. For Sierra Designs devices, investigate firmware updates from Sierra Designs directly. For Silicon Labs devices, check with the device manufacturer using S0 security for firmware updates. Network segmentation can limit the blast radius of a successful attack. Consider isolating the Z-Wave network from other critical networks. Regularly monitor Z-Wave traffic for anomalous activity. The Blackhat presentation linked in the references provides valuable insight into the vulnerability and potential exploitation techniques: https://sensepost.com/cms/resources/conferences/2013/bh_zwave/Security%20Evaluation%20of%20Z-Wave_WP.pdf. Also, refer to the Pentest Partners blog for details on downgrade attacks: https://www.pentestpartners.com/security-blog/z-shave-exploiting-z-wave-downgrade-attacks/.
4. Executive Summary
CVE-2013-20003 affects Z-Wave devices from Sierra Designs and Silicon Labs, potentially allowing attackers within radio range to spoof Z-Wave traffic due to the use of a simple, all-zeros network key. This could lead to compromised smart locks, disrupted lighting, or other disruptions depending on the devices in use. While the likelihood of a widespread, large-scale attack is moderate, the ease of exploitation is relatively high once an attacker is within range. The vulnerability impacts the integrity of the Z-Wave network, and potentially its availability. We recommend updating the firmware of affected devices, and if updates aren’t available, consider replacing vulnerable devices. Addressing this vulnerability is important to maintain the security and reliability of your smart home or building automation system, protecting against unauthorized access and potential disruptions. Prompt action will minimize the risk of a successful attack and maintain trust in the Z-Wave ecosystem.