CVE-2014-10374 in Activity Tracker
Summary
by MITRE
On Fitbit activity-tracker devices, certain addresses never change. According to the popets-2019-0036.pdf document, this leads to "permanent trackability" and "considerable privacy concerns" without a user-accessible anonymization feature. The devices, such as Charge 2, transmit Bluetooth Low Energy (BLE) advertising packets with a TxAdd flag indicating random addresses, but the addresses remain constant. If devices come within BLE range at one or more locations where an adversary has set up passive sniffing, the adversary can determine whether the same device has entered one of these locations.
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Analysis
by VulDB Data Team • 10/26/2023
The vulnerability described in CVE-2014-10374 represents a critical privacy flaw in Fitbit activity-tracker devices that fundamentally undermines user anonymity and tracking protection. This issue specifically affects devices such as the Charge 2 and similar models that utilize Bluetooth Low Energy (BLE) communication protocols for data transmission and device discovery. The core problem lies in the implementation of the BLE advertising packet structure where the TxAdd flag is set to indicate random addresses, yet the actual addresses transmitted remain static and unchanged across multiple sessions and locations. This technical inconsistency creates a persistent identifier that adversaries can exploit to establish long-term tracking capabilities without requiring active participation from device users.
The operational impact of this vulnerability extends far beyond simple location tracking, creating what researchers have termed "permanent trackability" that persists regardless of user awareness or device settings. When Fitbit devices operate within BLE range of passive monitoring equipment deployed at strategic locations such as retail stores, public spaces, or residential areas, the constant transmission of identical addresses allows adversaries to correlate device presence across time and space. This behavior directly violates fundamental privacy expectations for wearable devices and creates a persistent surveillance vector that operates independently of user consent or device configuration changes. The vulnerability manifests through the BLE advertising mechanism where devices continuously broadcast their identifiers, making it possible for any nearby passive listener to maintain a persistent record of device movements and patterns.
From a cybersecurity perspective, this vulnerability represents a clear violation of the principle of least privilege and user privacy protection, aligning with CWE-384, which addresses the use of predictable identifiers in security-sensitive contexts. The flaw also maps to ATT&CK technique T1566, specifically focusing on the use of wireless communications for reconnaissance and tracking purposes. The lack of user-accessible anonymization features compounds the issue, as users cannot effectively mitigate the tracking risk through device configuration changes or privacy settings. This creates a situation where even users who are aware of the privacy implications cannot protect themselves from persistent surveillance, fundamentally undermining the security model of the device and creating significant concerns for individuals who rely on wearable technology for personal health and fitness monitoring.
The implications of this vulnerability extend to broader privacy frameworks and regulatory compliance issues, particularly concerning the General Data Protection Regulation and similar privacy legislation that requires organizations to implement appropriate technical measures to protect personal data. The static nature of the BLE addresses means that even if users believe they have disabled tracking or changed their device settings, the underlying hardware implementation continues to provide persistent tracking capabilities. This vulnerability demonstrates the critical importance of proper implementation of privacy-by-design principles in IoT devices and highlights the gap between user expectations of privacy and the actual security posture of consumer wearable technology. Organizations deploying such devices in enterprise or healthcare environments face significant risks of unauthorized tracking and data collection that could compromise sensitive personal information and potentially violate privacy regulations.