CVE-2018-6402 in Ecobee
Summary
by MITRE
Ecobee Ecobee4 4.2.0.171 devices can be forced to deauthenticate and connect to an unencrypted Wi-Fi network with the same SSID, even if the device settings specify use of encryption such as WPA2, as long as the competing network has a stronger signal. An attacker must be able to set up a nearby SSID, similar to an "Evil Twin" attack.
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Analysis
by VulDB Data Team • 05/18/2024
This vulnerability affects ecobee4 smart thermostat devices running firmware version 4.2.0.171 and earlier, presenting a significant security risk through a sophisticated deauthentication attack vector. The flaw stems from the device's wireless network management behavior where it will automatically switch to connect to a nearby Wi-Fi network with the same SSID even when that network lacks encryption, provided the signal strength is stronger than the configured secure network. This behavior violates fundamental security principles by allowing devices to be tricked into connecting to unencrypted networks without proper authentication mechanisms, creating an attack surface that can be exploited by malicious actors positioned in close proximity to the target device.
The technical implementation of this vulnerability demonstrates a critical flaw in the device's wireless network selection algorithm, which prioritizes signal strength over security configuration settings. This represents a direct violation of security best practices where device configuration settings specifying WPA2 encryption are overridden by network signal strength metrics. The vulnerability is classified under CWE-310 as a weakness related to cryptographic issues, specifically concerning the improper handling of authentication mechanisms during network transitions. The attack requires an adversary to establish a competing Wi-Fi network with the same SSID but without encryption, effectively creating an "Evil Twin" scenario that exploits the device's trust in signal strength over security policies.
The operational impact of this vulnerability extends beyond simple network connectivity issues, as it fundamentally compromises the security posture of connected home environments. When an ecobee4 device connects to an unencrypted network, it exposes all communications between the device and its associated services to potential eavesdropping and man-in-the-middle attacks. The device's role as a central hub for home automation and climate control makes it particularly valuable to attackers who could potentially manipulate temperature settings, disable security features, or gain unauthorized access to other connected IoT devices within the network. This vulnerability aligns with ATT&CK technique T1046 which involves network service scanning and T1566 which covers credential harvesting through social engineering and network attacks.
Mitigation strategies must address both the immediate security gap and the underlying design flaw in the device's network management protocols. Users should immediately disable automatic network switching features if available, implement network segmentation to isolate IoT devices, and ensure that all Wi-Fi networks use strong encryption protocols such as WPA2 or WPA3. Network administrators should consider implementing wireless intrusion detection systems that can identify and alert on unauthorized access points with matching SSIDs. The most effective long-term solution involves firmware updates from ecobee that enforce strict adherence to configured security policies over signal strength metrics, ensuring that devices maintain their specified encryption requirements regardless of network conditions. Organizations should also consider implementing network access control policies that prevent devices from connecting to networks with weaker security configurations than their established settings.