CVE-2022-32506 in Nuki
Summary
by MITRE • 05/14/2024
An issue was discovered on certain Nuki Home Solutions devices. An attacker with physical access to the circuit board could use the SWD debug features to control the execution of code on the processor and debug the firmware, as well as read or alter the content of the internal and external flash memory. This affects Nuki Smart Lock 3.0 before 3.3.5, Nuki Smart Lock 2.0 before 2.12.4, as well as Nuki Bridge v1 before 1.22.0 and v2 before 2.13.2.
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Analysis
by VulDB Data Team • 08/20/2024
The vulnerability identified as CVE-2022-32506 represents a critical security flaw in Nuki Home Solutions smart lock and bridge devices that stems from improper hardware security implementation. This issue affects multiple generations of Nuki smart locks and bridges, specifically targeting the Nuki Smart Lock 3.0 before version 3.3.5, Nuki Smart Lock 2.0 before version 2.12.4, and both Nuki Bridge v1 before 1.22.0 and v2 before 2.13.2. The vulnerability resides in the device's hardware debugging interface, which remains accessible even when the device is deployed in production environments, creating a fundamental security weakness that directly violates the principle of secure by design.
The technical flaw manifests through the Serial Wire Debug (SWD) interface that is intentionally exposed on the circuit board for manufacturing and development purposes but remains enabled in final products. This interface provides direct access to the ARM Cortex-M processor's internal execution environment, allowing an attacker with physical access to the device to gain complete control over the system's operation. The SWD interface enables code execution control, firmware debugging capabilities, and direct memory access to both internal and external flash memory components. This represents a CWE-254 vulnerability category, specifically addressing security weaknesses related to inadequate access control and insufficient protection of development interfaces in embedded systems. The flaw essentially provides an attacker with a backdoor that bypasses all normal security mechanisms implemented in the device's firmware and operating system.
The operational impact of this vulnerability is severe and multifaceted, as it allows for complete device compromise through physical access alone. An attacker can not only read sensitive data stored in flash memory including cryptographic keys, user credentials, and access logs but can also modify the firmware to create persistent backdoors or alter the device's behavior to enable unauthorized access. The ability to control code execution means that attackers can modify the smart lock's operation to disable security features, create false access records, or even allow remote access through the compromised device. This vulnerability directly maps to ATT&CK technique T1211 which involves manipulating processes and services to achieve persistence and maintain access to compromised systems. The implications extend beyond individual device compromise to potentially affect entire smart home ecosystems, as compromised locks could serve as entry points for broader network infiltration.
The security implications of CVE-2022-32506 are particularly concerning given that physical access to a smart lock is often considered a low-barrier attack vector that many security professionals might not adequately consider. The vulnerability demonstrates a critical failure in hardware security design where development interfaces that should be disabled in production devices remain accessible, creating an inherent weakness that cannot be addressed through software patches alone. Organizations and individuals deploying these devices face significant risks, as the vulnerability affects not just the device itself but potentially the entire security infrastructure that relies on these locks for access control. The fix requires hardware-level modifications to disable or secure the SWD interface, which is typically not possible through firmware updates, making this vulnerability particularly challenging to remediate. This represents a fundamental breach of the principle of least privilege and demonstrates how embedded system security must consider all potential attack surfaces, including physical access points and development interfaces that are commonly overlooked in traditional security assessments.