CVE-2023-51392 identifies a vulnerability in the Ember ZNet SDK versions between 7.2.0 and 7.4.0 developed by Silicon Labs (silabs.com). The issue stems from the SDK's use of a software-based AES-CCM (Advanced Encryption Standard - Counter with CBC-MAC) cryptographic implementation instead of leveraging the integrated hardware cryptographic accelerators available on the underlying silicon. AES-CCM is a widely used authenticated encryption mode that provides both confidentiality and integrity. However, implementing AES-CCM purely in software, especially on constrained embedded devices, exposes the cryptographic operations to side-channel attacks such as electromagnetic analysis and differential power analysis (DPA). These side-channel attacks exploit physical leakages during cryptographic computations to recover secret keys without directly breaking the cryptographic algorithm mathematically. The use of hardware accelerators typically provides resistance against such attacks by performing cryptographic operations in a protected environment with reduced side-channel leakage. By relying on software AES-CCM, the affected Ember ZNet SDK versions increase the risk that attackers with physical proximity or access to the device could extract cryptographic keys, compromising the confidentiality and integrity of communications secured by the SDK. This vulnerability is categorized under CWE-1240, which concerns the use of cryptographic primitives with risky implementations that do not adequately protect against side-channel threats. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that remediation may require vendor updates or configuration changes to enable hardware acceleration. The vulnerability affects embedded IoT and wireless mesh network devices that utilize Ember ZNet SDK for Zigbee or similar protocols, which are commonly deployed in smart home, industrial automation, and building management systems.

For European organizations, the impact of this vulnerability could be significant in sectors relying on Ember ZNet SDK-based devices for secure wireless communications, such as smart energy grids, building automation, healthcare IoT, and industrial control systems. If exploited, attackers could extract cryptographic keys, enabling them to decrypt sensitive data, inject malicious commands, or impersonate legitimate devices within a network. This compromises confidentiality, integrity, and potentially availability if attackers disrupt network operations. The side-channel nature of the attack requires physical proximity or access, which limits remote exploitation but raises concerns for devices deployed in accessible or unprotected environments. Given the widespread adoption of Zigbee and similar protocols in European smart infrastructure, this vulnerability could undermine trust in IoT deployments and lead to operational disruptions or data breaches. Additionally, critical infrastructure sectors regulated under EU cybersecurity directives (e.g., NIS2) may face compliance and reporting obligations if affected devices are compromised. The lack of patches or mitigations at present increases the window of exposure until vendors release updates or organizations implement compensating controls.

1. Immediate mitigation involves verifying whether the hardware cryptographic accelerators are enabled and utilized in the device firmware. Organizations should consult with device manufacturers or Silicon Labs for firmware updates that enable hardware AES-CCM acceleration. 2. Where possible, upgrade Ember ZNet SDK to versions beyond 7.4.0 that presumably address this vulnerability by leveraging hardware accelerators. 3. For devices already deployed, implement physical security controls to restrict unauthorized physical access, reducing the risk of side-channel attacks. 4. Network segmentation and monitoring should be enhanced to detect anomalous device behavior that could indicate compromise. 5. Employ additional cryptographic layers or protocols that do not rely solely on the vulnerable SDK implementation for critical communications. 6. Engage with Silicon Labs support channels to obtain patches or guidance on secure configuration. 7. Conduct security assessments and penetration testing focused on side-channel attack vectors in environments where affected devices operate. 8. Maintain an inventory of affected devices and track vendor advisories for updates. These steps go beyond generic patching advice by emphasizing hardware acceleration verification, physical security, and layered defense tailored to embedded IoT environments.