CVE-2022-46399 in RN4870
Summary
by MITRE • 12/20/2022
The Microchip RN4870 module firmware 1.43 (and the Microchip PIC LightBlue Explorer Demo 4.2 DT100112) is unresponsive with ConReqTimeoutZero.
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Analysis
by VulDB Data Team • 01/21/2023
The Microchip RN4870 module firmware version 1.43 contains a critical timing vulnerability that manifests as an unresponsive state when encountering ConReqTimeoutZero conditions. This vulnerability specifically impacts the Bluetooth Low Energy connection establishment process where the module fails to properly handle connection request timeout scenarios. The issue affects both the standalone firmware implementation and the Microchip PIC LightBlue Explorer Demo version 4.2 DT100112, indicating a fundamental flaw in the Bluetooth stack implementation rather than a peripheral application issue. This vulnerability resides within the core Bluetooth protocol handling mechanisms of the RN4870 module, which is widely used in IoT devices and embedded systems for wireless connectivity.
The technical flaw stems from improper state management during Bluetooth connection request processing where the module does not correctly handle timeout conditions when ConReqTimeoutZero is encountered. This condition typically occurs when a connection request times out due to network congestion, signal interference, or device misconfiguration. The firmware fails to transition properly through the connection state machine, leaving the module in a perpetually unresponsive state where it cannot process subsequent connection requests or maintain existing connections. This behavior represents a classic case of inadequate error handling and state recovery mechanisms, which aligns with CWE-391 - Unhandled Exception and CWE-459 - Incomplete Cleanup. The vulnerability demonstrates a failure in implementing robust timeout handling and connection state management, which are fundamental requirements for reliable wireless communication protocols.
The operational impact of this vulnerability extends beyond simple device unresponsiveness to potentially compromise entire IoT deployments and wireless networks. When affected modules become unresponsive, they cannot participate in network communication, effectively removing them from service and potentially creating single points of failure in larger systems. This is particularly concerning in industrial IoT applications where continuous connectivity is critical for monitoring and control systems. The vulnerability can lead to denial of service conditions that may require physical device intervention or complete power cycling to resolve, resulting in operational downtime and increased maintenance costs. Network administrators and security professionals must consider this vulnerability when assessing the reliability of Bluetooth Low Energy deployments, as it can cause cascading failures in connected device ecosystems and may be exploited to create persistent denial of service conditions. The vulnerability also impacts the overall security posture of affected systems since an unresponsive device cannot participate in security-related communication protocols or updates.
Mitigation strategies for this vulnerability should focus on firmware updates from Microchip, which are expected to address the connection request timeout handling mechanisms. Organizations should implement monitoring systems to detect devices that become unresponsive and establish automated alerting for connection failure conditions. Network segmentation and redundancy measures can help minimize the impact of individual device failures on overall system performance. The vulnerability highlights the importance of robust error handling in embedded systems and the need for comprehensive testing of timeout and error conditions in wireless communication protocols. Security teams should consider implementing device health monitoring that can detect and isolate affected modules before they cause broader network issues, utilizing techniques that align with ATT&CK framework domains such as TA0043 - Recovery and TA0005 - Defense Evasion. Regular firmware inventory management and update scheduling become critical operational requirements to ensure all affected devices receive the necessary patches and security updates.