Dr.-Ing. Flor Maria Alvarez Zurita

Contact Information

Offered Theses Topics

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  2019 Completed

Security Analysis of LoRaWAN: An Experimental Evaluation of Attacks

Supervisor: Lars Almon Flor Maria Alvarez Zurita

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Low-power wide-area networks (LPWAN) are becoming the wireless backbone for modern business processes and municipal administration. LoRaWAN, which stands for long-range wide-area network, is a recent medium access control (MAC) layer protocol competing for this market. It stands out by its open operator model and a novel modulation technique. With LoRaWAN and other communication technologies are becoming a dependency for more and more aspects of today's society, the question for their security and reliability comes up. Previous researches on the topic have already revealed vulnerabilities in the first LoRaWAN specification, which have been partly mitigated in the most recent LoRaWAN 1.1. However, related studies often provide only theoretical results or consider practical scenarios only on a specific, small scale. In this thesis, we present a LoRaWAN security evaluation framework that allows field-testing the security and reliability characteristics of actual LoRaWAN deployments. This provides not only reproducible results but also allows making a comparison between defined versions of the specification and LoRaWAN software. Before expounding implementation details, we provide a literature survey on LoRaWAN vulnerabilities and attacks to identify interesting aspects for further evaluation. From our experimental results, we show that jamming is a serious threat to the availability of LoRaWAN networks. Furthermore, we demonstrate the practical applicability of two replay attacks against a selection of LoRaWAN software and illustrate why they will remain relevant for years due to backward compatibility.

  2017 Completed

Reverse Engineering the Apple Wireless Direct Link Protocol

Supervisor: Milan Stute Flor Maria Alvarez Zurita

Apple Wireless Direct Link (AWDL) is a proprietary and undocumented 802.11 based peer-to-peer protocol. It is implemented in all of Apple's operating systems. In this thesis a reverse engineering method using binary analysis complemented by runtime analysis with traces and logs was applied. We found that each device in AWDL provides its own channel sequence. An elected master node is used to synchronize these sequences. Outside these windows of time, devices can use their wireless radio for other protocols or save energy by turning it off. Each node adapts its channel sequence, e.g. depending on network load, shifting the ratio between infrastructure and peer-to-peer Wi-Fi. This thesis also provides a first analysis of AWDL, includes the frame format documentation and presents a Wireshark dissector and a prototype implementation for AWDL.

  2016 Completed

A Framework for Adaptive Energy-efficient Neighbour Discovery in Oppertunistic Networks

Supervisor: Flor Maria Alvarez Zurita

  2016 Completed

Secure key exchange protocol for a group communication during emergency responses

Supervisor: Flor Maria Alvarez Zurita

Publications

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  2020  13th ACM Conference on Security and Privacy in Wireless and Mobile Networks Conference

Acoustic Integrity Codes: Secure Device Pairing Using Short-Range Acoustic Communication

Florentin Putz Flor Álvarez Jiska Classen

PDF BibTeX DOI: 10.1145/3395351.3399420

Abstract
Secure Device Pairing (SDP) relies on an out-of-band channel to authenticate devices. This requires a common hardware interface, which limits the use of existing SDP systems. We propose to use short-range acoustic communication for the initial pairing. Audio hardware is commonly available on existing off-the-shelf devices and can be accessed from user space without requiring firmware or hardware modifications. We improve upon previous approaches by designing Acoustic Integrity Codes (AICs): a modulation scheme that provides message authentication on the acoustic physical layer. We analyze their security and demonstrate that we can defend against signal cancellation attacks by designing signals with low autocorrelation. Our system can detect overshadowing attacks using a ternary decision function with a threshold. In our evaluation of this SDP scheme’s security and robustness, we achieve a bit error ratio below 0.1% for a net bit rate of 100 bps with a signal-to-noise ratio (SNR) of 14 dB. Using our open-source proof-of-concept implementation on Android smartphones, we demonstrate pairing between different smartphone models.