CVE-2021-27952 in ecobee3 lite
Summary
by MITRE • 08/03/2021
Hardcoded default root credentials exist on the ecobee3 lite 4.5.81.200 device. This allows a threat actor to gain access to the password-protected bootloader environment through the serial console.
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Analysis
by VulDB Data Team • 08/07/2021
The vulnerability identified as CVE-2021-27952 represents a critical security flaw in the ecobee3 lite thermostat device running firmware version 4.5.81.200. This issue stems from the improper implementation of authentication mechanisms within the device's bootloader environment, creating an exploitable pathway for unauthorized access. The presence of hardcoded credentials fundamentally undermines the device's security posture and creates a persistent backdoor that can be leveraged by threat actors to gain deep system access.
The technical flaw manifests through the use of hardcoded default root credentials that are embedded within the device's firmware during the manufacturing process. These credentials are not only persistent but are also accessible through the serial console interface, which serves as a direct communication channel to the device's underlying operating system. The vulnerability specifically affects the bootloader environment, which is responsible for initializing the device's operating system and typically requires elevated privileges to access. This design flaw allows threat actors to bypass normal authentication procedures and gain immediate administrative access to the device's core systems.
From an operational impact perspective, this vulnerability creates significant risks for both individual users and enterprise environments that deploy these devices. The threat actor can exploit this weakness to gain complete control over the device, potentially enabling them to modify device settings, access sensitive environmental data, or use the device as a pivot point for attacking other networked systems. The serial console access provides a direct pathway to system-level operations, making this vulnerability particularly dangerous as it allows for arbitrary code execution and potential privilege escalation. The persistent nature of hardcoded credentials means that this vulnerability remains exploitable across device reboots and firmware updates unless explicitly addressed.
Security professionals should consider this vulnerability in the context of the broader attack surface and potential lateral movement opportunities it provides. The presence of hardcoded credentials aligns with CWE-798, which identifies the use of hardcoded credentials as a significant security weakness, and may also relate to CWE-259, which addresses the use of weak password mechanisms. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and privilege escalation, potentially enabling threat actors to establish persistence and conduct reconnaissance within affected networks. Organizations should implement immediate mitigations including firmware updates from the vendor, network segmentation to limit access to affected devices, and monitoring for unusual serial console activity to detect potential exploitation attempts.