Mobile applications transmit sensitive data and user identifiers to domain-based endpoints embedded in SDKs and third-party services. Unlike the web, where operators can update or remove third-party endpoints, apps are static binaries that remain installed for years and continue sending identifiers to endpoints whose domains may expire, change ownership, or become abandoned. This mismatch creates a privacy risk, since identifiers may flow to hijacked, unmaintained, or maliciously re-registered endpoints without users' knowledge or consent. This work presents a privacy risk analysis of domain endpoints in Android apps. We identify endpoints receiving sensitive identifiers through dynamic analysis of 11,131 apps and track the lifecycle of 3,420 associated domains around their expiration events. Our analysis reveals that 25.3% of domains are renewed after expiration, with 78.7% of these belonging to third-party services or SDKs embedded in apps whose install brackets total over 78 billion cumulative downloads, placing a potential user base of billions at risk. While the majority of these lapses are short and fall within registrar grace periods, we identify 218 domains with dangling CNAMEs susceptible to subdomain hijacking (34 of which received 91 valid TLS certificates during their expired period), and show that 17.0% of domains experience TLS issuance gaps where confidentiality is lost. We categorize high-risk endpoints into Advertising and Tracking vs Backend and Utility services, finding that vulnerable endpoints are embedded in over 4,000 apps. By correlating WHOIS, DNS, and TLS lifecycles with dynamically observed identifier flows, we expose how domain mismanagement translates into data flows and user privacy harm. Finally, we derive mitigation strategies to address these supply-chain risks.

Over the past few years, the two dominant app platforms made major improvements to their policies surrounding child-directed apps. While prior work repeatedly demonstrated that privacy issues were prevalent in child-directed apps, it is unclear whether platform policies can lead child-directed apps to comply with privacy requirements, when laws alone have not. To understand the effect of recent changes in platform policies (e.g., whether they result in greater levels of compliance with applicable privacy laws), we conducted a large-scale measurement study of the privacy behaviors of 7,377 child-directed Android apps, as well as a follow-up survey with some of their developers. We observed a drastic decrease in the number of apps that transmitted personal data without verifiable parental consent and an increase in the number of apps that encrypted their transmissions using TLS. However, improper use of third-party SDKs still led to privacy issues (e.g., inaccurate disclosures in apps’ privacy labels). Our analysis of apps’ privacy practices over a period of a few months in 2023 and a comparison of our results with those observed a few years ago demonstrate gradual improvements in apps’ privacy practices over time. We discuss how app platforms can further improve their policies and emphasize the role of enforcement in making such policies effective.

Mobile apps frequently use Bluetooth Low Energy (BLE) and WiFi scanning permissions to discover nearby devices like peripherals and connect to WiFi Access Points (APs). However, wireless interfaces also serve as a covert proxy for geolocation data, enabling continuous user tracking and profiling. This includes technologies like BLE beacons, which are BLE devices broadcasting unique identifiers to determine devices' indoor physical locations; such beacons are easily found in shopping centres. Despite the widespread use of wireless scanning APIs and their potential for privacy abuse, the interplay between commercial mobile SDKs with wireless sensing and beaconing technologies remains largely unexplored. In this work, we conduct the first systematic analysis of 52 wireless-scanning SDKs, revealing their data collection practices and privacy risks. We develop a comprehensive analysis pipeline that enables us to detect beacon scanning capabilities, inject wireless events to trigger app behaviors, and monitor runtime execution on instrumented devices. Our findings show that 86% of apps integrating these SDKs collect at least one sensitive data type, including device and user identifiers such as AAID, email, along with GPS coordinates, WiFi and Bluetooth scan results. We uncover widespread SDK-to-SDK data sharing and evidence of ID bridging, where persistent and resettable identifiers are shared and synchronized within SDKs embedded in applications to potentially construct detailed mobility profiles, compromising user anonymity and enabling long-term tracking. We provide evidence of key actors engaging in these practices and conclude by proposing mitigation strategies such as stronger SDK sandboxing, stricter enforcement of platform policies, and improved transparency mechanisms to limit unauthorized tracking.

The network communication between Internet of Things (IoT) devices on the same local network has significant implications for platform and device interoperability, security, privacy, and correctness. Yet, the analysis of local home Wi-Fi network traffic and its associated security and privacy threats have been largely ignored by prior literature, which typically focuses on studying the communication between IoT devices and cloud end-points, or detecting vulnerable IoT devices exposed to the Internet. In this paper, we present a comprehensive and empirical measurement study to shed light on the local communication within a smart home deployment and its threats. We use a unique combination of passive network traffic captures, protocol honeypots, dynamic mobile app analysis, and crowdsourced IoT data from participants to identify and analyze a wide range of device activities on the local network. We then analyze these datasets to characterize local network protocols, security and privacy threats associated with them. Our analysis reveals vulnerable devices, insecure use of network protocols, and sensitive data exposure by IoT devices. We provide evidence of how this information is exfiltrated to remote servers by mobile apps and third-party SDKs, potentially for household fingerprinting, surveillance and cross-device tracking. We make our datasets and analysis publicly available to support further research in this area.

The ability to identify the author responsible for a given software object is critical for many research studies and for enhancing software transparency and accountability. However, as opposed to other application markets like Apple's iOS App Store, attribution in the Android ecosystem is known to be hard. Prior research has leveraged market metadata and signing certificates to identify software authors without questioning the validity and accuracy of these attribution signals. However, Android application (app) authors can, either intentionally or by mistake, hide their true identity due to: (1) the lack of policy enforcement by markets to ensure the accuracy and correctness of the information disclosed by developers in their market profiles during the app release process, and (2) the use of self-signed certificates for signing apps instead of certificates issued by trusted CAs. In this paper, we perform the first empirical analysis of the availability, volatility and overall aptness of publicly available market and app metadata for author attribution in Android markets. To that end, we analyze a dataset of over 2.5 million market entries and apps extracted from five Android markets for over two years. Our results show that widely used attribution signals are often missing from market profiles and that they change over time. We also invalidate the general belief about the validity of signing certificates for author attribution. For instance, we find that apps from different authors share signing certificates due to the proliferation of app building frameworks and software factories. Finally, we introduce the concept of anattribution graphand we apply it to evaluate the validity of existing attribution signals on the Google Play Store. Our results confirm that the lack of control over publicly available signals can confuse automatic attribution processes.

The IoT ecosystem is an intricate and complex network of stakeholders that includes platforms, developers, ad networks and cloud providers. However, the ability of smart home platforms and devices to interact and exchange data, together with the data-driven business models adopted by most IoT stakeholders open the ground for unknown and unexpected privacy risks. Existing black-box testing approaches to audit IoT platforms cannot identify data dissemination through side- and covert-channels, and for this reason they are not well suited for rich execution environments where a wide range of devices and applications can co-operate using multiple network protocols and interfaces. This poster proposes ImposTer, a cost-effective and extensible privacy framework for exhaustively testing the IoT ecosystem. Our framework is able to capture, model and emulate horizontal interactions that occur across the different devices in a consumer household.