Muslum Ozgur Ozmen

Distributed systems are fundamental to modern computing infrastructures, enabling scalability, fault tolerance, and efficient resource sharing. To maintain a consistent view of resources and support data replication across network nodes, systems such as distributed databases, cloud infrastructures, and decentralized storage rely on consensus algorithms. However, these algorithms are increasingly targeted by sophisticated attacks, threatening not only system integrity but also network-wide consistency. In this survey, we 1) systematically classify consensus algorithms employed for data replication in distributed systems, covering their operation, strengths, limitations, and deployment contexts, and 2) analyze attacks that compromise their integrity, categorizing them according to strategy and targeted vulnerabilities. We review mitigation mechanisms and evaluate algorithmic resilience, drawing from both peer-reviewed and grey literature. Beyond literature aggregation, we identify cross-cutting weaknesses, such as overreliance on benign fault models, and highlight the lack of robust defenses against strategic adversaries. Our analysis reveals that many systems continue to treat targeted attacks as transient faults, underestimating their impact on consistency guarantees. By exposing these gaps and synthesizing known defenses, our study provides a foundation for future research aimed at securing consensus protocols in distributed data replication settings.

The rising popularity of mental wellbeing technologies has led many individuals to explore binaural beats—an emerging form of sound therapy proliferating on web and mobile platforms. However, it currently remains unknown whether users can trust binaural tracks on online platforms, or if they deceive unsuspecting users. Our research aims to address this problem by understanding (1) what binaural beats listeners expect from tracks and (2) whether online tracks conform to these expectations. To understand user expectations, we perform thematic analysis on online forum threads and blog posts to extract binaural beats goals and expectations tied to these goals. Next, we design a methodology to measure binaural beats tracks’ conformance to commonly held user expectations. This methodology comprises, (1) obtaining a track’s intent to induce a mental state through track metadata analysis, (2) extracting a track’s binaural beats time-frequency model using Fast Fourier Transform, (3) mapping user expectations to rules that identify deceptive tracks, and validating them on the track’s extracted intent and time-frequency model. We evaluate ∼7K binaural beats tracks and find that only 7.5% conform to commonly held user expectations, while the remaining 92.5% deceive users with deviant claims (e.g., eroticism, weight loss) or deliver contradicting binaural beats. Our study underscores the significance of understanding users’ expectations and verifying conformance of online wellness technologies to expose discrepancies in expectations.

In Voice Assistant (VA) platforms, when users add devices to their accounts and give voice commands, complex interactions occur between the devices, skills, VA clouds, and vendor clouds. These interactions are governed by the device management capabilities (DMC) of VA platforms, which rely on device names, types, and associated skills in the user account. Prior work studied vulnerabilities in specific VA components, such as hidden voice commands and bypassing skill vetting. However, the security and privacy implications of device management flaws have largely been unexplored. In this paper, we introduce DMC-Xplorer, a testing framework for the automated discovery of VA device management flaws. We first introduce VA description language (VDL), a new domain-specific language to create VA environments for testing, using VA and skill developer APIs. DMC-Xplorer then selects VA parameters (device names, types, vendors, actions, and skills) in a combinatorial approach and creates VA environments with VDL. It issues real voice commands to the environment via developer APIs and logs event traces. It validates the traces against three formal security properties that define the secure operation of VA platforms. Lastly, DMC-Xplorer identifies the root cause of property violations through intervention analysis to identify VA device management flaws. We exercised DMC-Xplorer on Amazon Alexa and Google Home and discovered two design flaws that can be exploited to launch four attacks. We show that malicious skills with default permissions can eavesdrop on privacy-sensitive device states, prevent users from controlling their devices, and disrupt the services on the VA cloud.

Mental wellbeing technologies are prevalent in digital spaces, such as content creation websites (e.g., YouTube) and mobile apps. Many users leverage such technologies and thus develop expectations for what they should provide. However, tools to verify whether these technologies conform to user expectations remain largely unexplored. We investigate this problem in the domain of binaural beats - a popular mental wellbeing technology. Using results from preliminary research, where we establish commonly held user expectations and introduce a method to measure expectation conformance, we explore the design of a tool to be used by binaural beats listeners. Through a pre-design survey with 43 participants and a user study with 28 participants, we demonstrate how tools leveraging commonly held user expectations can help users of mental wellbeing applications make informed decisions.

There is a growing interest in integrating Large Language Models (LLMs) with autonomous driving (AD) systems. However, AD systems are vulnerable to attacks against their object detection and tracking (ODT) functions. Unfortunately, our evaluation of four recent LLM agents against ODT attacks shows that the attacks are 63.26% successful in causing them to crash or violate traffic rules due to (1) misleading memory modules that provide past experiences for decision making, (2) limitations of prompts in identifying inconsistencies, and (3) reliance on ground truth perception data. In this paper, we introduce Hudson, a driving reasoning agent that extends prior LLM-based driving systems to enable safer decision making during perception attacks while maintaining effectiveness under benign conditions. Hudson achieves this by first instrumenting the AD software to collect real-time perception results and contextual information from the driving scene. This data is then formalized into a domain-specific language (DSL). To guide the LLM in detecting and making safe control decisions during ODT attacks, Hudson translates the DSL into natural language, along with a list of custom attack detection instructions. Following query execution, Hudson analyzes the LLM's control decision to understand its causal reasoning process. We evaluate the effectiveness of Hudson using a proprietary LLM (GPT-4) and two open-source LLMs (Llama and Gemma) in various adversarial driving scenarios. GPT-4, Llama, and Gemma achieve, on average, an attack detection accuracy of 83. 3%, 63. 6%, and 73. 6%. Consequently, they make safe control decisions in 86.4%, 73.9%, and 80% of the attacks. Our results, following the growing interest in integrating LLMs into AD systems, highlight the strengths of LLMs and their potential to detect and mitigate ODT attacks.