arXiv subjects

Matthias Hollick

Publications and source records attributed to Matthias Hollick.

76 records · Page 5Linked to original sources

arXiv2017

Survey and Systematization of Secure Device Pairing

Secure Device Pairing (SDP) schemes have been developed to facilitate secure communications among smart devices, both personal mobile devices and Internet of Things (IoT) devices. Comparison and assessment of SDP schemes is troublesome, because each scheme makes different assumptions about out-of-band channels and adversary models, and are driven by their particular use-cases. A conceptual model that facilitates meaningful comparison among SDP schemes is missing. We provide such a model. In this article, we survey and analyze a wide range of SDP schemes that are described in the literature, including a number that have been adopted as standards. A system model and consistent terminology for SDP schemes are built on the foundation of this survey, which are then used to classify existing SDP schemes into a taxonomy that, for the first time, enables their meaningful comparison and analysis.The existing SDP schemes are analyzed using this model, revealing common systemic security weaknesses among the surveyed SDP schemes that should become priority areas for future SDP research, such as improving the integration of privacy requirements into the design of SDP schemes. Our results allow SDP scheme designers to create schemes that are more easily comparable with one another, and to assist the prevention of persisting the weaknesses common to the current generation of SDP schemes.

cs.CR↗

arXiv2017

Breaking Fitness Records without Moving: Reverse Engineering and Spoofing Fitbit

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 the devices we analyze. 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.

cs.CR↗

arXiv2015

NexMon: A Cookbook for Firmware Modifications on Smartphones to Enable Monitor Mode

Full control over a Wi-Fi chip for research purposes is often limited by its firmware, which makes it hard to evolve communication protocols and test schemes in practical environments. Monitor mode, which allows eavesdropping on all frames on a wireless communication channel, is a first step to lower this barrier. Use cases include, but are not limited to, network packet analyses, security research and testing of new medium access control layer protocols. Monitor mode is generally offered by SoftMAC drivers that implement the media access control sublayer management entity (MLME) in the driver rather than in the Wi-Fi chip. On smartphones, however, mostly FullMAC chips are used to reduce power consumption, as MLME tasks do not need to wake up the main processor. Even though, monitor mode is also possible in FullMAC scenarios, it is generally not implemented in today's Wi-Fi firmwares used in smartphones. This work focuses on bringing monitor mode to Nexus 5 smartphones to enhance the interoperability between applications that require monitor mode and BCM4339 Wi-Fi chips. The implementation is based on our new C-based programming framework to extend existing Wi-Fi firmwares.

cs.OH↗

arXiv2015

Practical Covert Channels for WiFi Systems

Wireless covert channels promise to exfiltrate information with high bandwidth by circumventing traditional access control mechanisms. Ideally, they are only accessible by the intended recipient and---for regular system users/operators---indistinguishable from normal operation. While a number of theoretical and simulation studies exist in literature, the practical aspects of WiFi covert channels are not well understood. Yet, it is particularly the practical design and implementation aspect of wireless systems that provides attackers with the latitude to establish covert channels: the ability to operate under adverse conditions and to tolerate a high amount of signal variations. Moreover, covert physical receivers do not have to be addressed within wireless frames, but can simply eavesdrop on the transmission. In this work, we analyze the possibilities to establish covert channels in WiFi systems with emphasis on exploiting physical layer characteristics. We discuss design alternatives for selected covert channel approaches and study their feasibility in practice. By means of an extensive performance analysis, we compare the covert channel bandwidth. We further evaluate the possibility of revealing the introduced covert channels based on different detection capabilities.

cs.NI↗