Breaking Fitness Records without Moving: Reverse Engineering and Spoofing Fitbit

Hossein Fereidooni, Jiska Classen, Tom Spink, Paul Patras, Markus Miettinen, Ahmad-Reza Sadeghi, Matthias Hollick, Mauro Conti

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Tens of millions of wearable fitness trackers are shipped yearly to consumers who routinely collect information about their exercising patterns. Smartphones push this health-related data to vendors' cloud platforms, enabling users to analyze summary statistics on-line and adjust their habits. Third-parties including health insurance providers now offer discounts and financial rewards in exchange for such private information and evidence of healthy lifestyles. Given the associated monetary value, the authenticity and correctness of the activity data collected becomes imperative.

In this paper, we provide an in-depth security analysis of the operation of fitness trackers commercialized by Fitbit, the wearables market leader. We reveal an intricate security through obscurity approach implemented by the user activity synchronization protocol running on these devices. Although non-trivial to interpret, we reverse engineer the message semantics, demonstrate how falsified user activity reports can be injected, and argue that based on our discoveries, such attacks can be performed at scale to obtain financial gains. We further document a hardware attack vector that enables circumvention of the end-to-end protocol encryption present in the latest Fitbit firmware, leading to the spoofing of valid encrypted fitness data. Finally, we give guidelines for avoiding similar vulnerabilities in future system designs.
Original languageEnglish
Title of host publicationResearch in Attacks, Intrusions, and Defenses (RAID 2017)
PublisherSpringer, Cham
Number of pages22
ISBN (Electronic)978-3-319-66332-6
ISBN (Print)978-3-319-66331-9
Publication statusPublished - 2017
EventResearch in Attacks, Intrusions, and Defenses 2017 - Atlanta, United States
Duration: 18 Sep 201720 Sep 2017

Publication series

NameLecture Notes in Computer Science
PublisherSpringer, Cham
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


ConferenceResearch in Attacks, Intrusions, and Defenses 2017
Abbreviated titleRAID 2017
CountryUnited States
Internet address

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