CVE-2017-9657 in IntelliVue MX40
Summary
by MITRE
Under specific 802.11 network conditions, a partial re-association of the Philips IntelliVue MX40 Version B.06.18 WLAN monitor to the central monitoring station is possible. In this state, the central monitoring station can indicate the MX40 is not connected or associated to the central monitor, and thus should be operating in local monitoring mode (local audio-on, screen-on), but the MX40 WLAN itself can instead still be operating in telemetry mode (local audio-off, screen-off). If a patient experiences an alarm event and clinical staff expects the MX40 to provide local alarming when it is not available from the local device, a delay of treatment can occur. CVSS v3 base score: 6.5, CVSS vector string: AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Philips has released software update, Version B.06.18, to fix the improper cleanup on thrown exception vulnerability, and implement mitigations to reduce the risk associated with the improper handling of exceptional conditions vulnerability. The software update implements messaging and alarming on the MX40 and at the central monitoring station, when the MX40 disconnects from the access point.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 02/01/2020
The vulnerability described in CVE-2017-9657 affects Philips IntelliVue MX40 Version B.06.18 wireless patient monitoring devices operating within 802.11 network environments. This issue represents a critical operational failure in the device's wireless communication management system where partial re-association conditions can occur during network transitions. The flaw manifests when the monitoring station incorrectly reports the device as disconnected while the device itself maintains its wireless telemetry connection in a different operational state. This creates a dangerous misalignment between the central monitoring system's perception of device status and the actual device behavior, fundamentally compromising patient safety protocols.
The technical root cause of this vulnerability lies in improper exception handling mechanisms within the device's wireless communication stack. When network conditions trigger exception scenarios during the re-association process, the system fails to properly clean up its operational state, resulting in inconsistent device behavior. This aligns with CWE-252, which addresses "Unchecked Return Value" conditions where the system does not properly validate or handle exceptional conditions that should terminate or reset operational states. The vulnerability specifically demonstrates poor error recovery implementation that leaves the device in an ambiguous operational state rather than gracefully transitioning to a known safe mode.
The operational impact of this vulnerability extends beyond simple communication issues to potentially life-threatening delays in patient care. When the central monitoring station incorrectly indicates device disconnection, clinical staff may assume the device has failed and rely on local monitoring capabilities that are actually unavailable. The device maintains telemetry mode with local audio-off and screen-off settings, creating a false sense of security while simultaneously disabling critical alarm notifications. This scenario directly violates the principle of fail-safe operation in medical devices, where system failures should result in clearly defined safe states rather than ambiguous conditions. The CVSS score of 6.5 reflects the high potential for harm when this vulnerability is exploited during critical patient monitoring situations.
The vulnerability creates a significant attack surface that could be exploited through network manipulation or environmental conditions that trigger the specific 802.11 re-association scenarios. Attackers could potentially force the device into this partial re-association state through network interference or by creating specific wireless conditions that cause the device to attempt re-association while maintaining its telemetry connection. This aligns with ATT&CK technique T1484.001 which addresses "Abuse of Functionality" where legitimate system features are manipulated to achieve unintended operational states. The device's response to exceptional network conditions demonstrates insufficient input validation and error recovery mechanisms that should be implemented according to medical device security standards.
Philips addressed this vulnerability through a comprehensive software update that implements proper exception handling procedures and enhanced communication protocols between the device and central monitoring station. The update specifically targets the improper cleanup on thrown exception vulnerability by ensuring that when network re-association failures occur, the device properly transitions to a known safe state rather than maintaining ambiguous operational conditions. The implementation includes improved messaging protocols that provide clear status indication to both the device and central monitoring station when disconnection events occur. This update also incorporates enhanced alarming mechanisms that ensure clinical staff receive immediate notification when device connectivity issues are detected, preventing the dangerous delay in treatment that could occur during the vulnerable state. The solution demonstrates adherence to proper software engineering practices for safety-critical systems and addresses the underlying architectural weakness in the device's wireless communication error handling.