Doxing refers to the disclosure of personal information without consent, has evolved from sporadic acts of online vigilantism into a structured and commodified practice. In Chinese cyberspace, this shift has produced Doxing-as-a-Service (DaaS), a commercial model in which personal data is retrieved, organized, and traded as on-demand products. This industrialization of privacy violation lowers the barriers to doxing and amplifies its social harms, posing new challenges for building a responsible and safe web. Yet little is known about how DaaS operates or sustains itself, motivating our systematic, data-driven examination of its ecosystem and practices. This paper provides the first systematic study of the Chinese DaaS ecosystem. Analyzing 25,972 messages and 13.22 million subscriber links from 100 major channels on Telegram, we demystify its organization, operations, and user engagement. We find that the DaaS ecosystem operates through a three-tier supply chain linking data providers, service operators, and end users. Operators sustain illicit businesses through six major service categories, persistent advertising, and crypto-based payments, while users interact via specialized group spaces that enable real-time matching, large-scale identity exposure, and community-driven fraud mitigation. Our findings reveal a mature, resilient underground data market operating within mainstream messaging platforms, highlighting new challenges for online privacy and exposing critical vulnerabilities in platform governance and content moderation. This study provides empirical evidence for developing effective regulatory frameworks and accountability mechanisms to mitigate commodified online harms on encrypted messaging services.

App stores allow developers to globally distribute their apps to gain more users and attention. In the highly competitive market of app stores, developers need to cater to a large number of users spanning multiple countries. We posit that the characteristics of diverse geographical, linguistic, cultural, societal, and economic environments may impact the adoption of apps. In this paper, we take the first step to characterize popular apps across over 150 countries worldwide, and explore the potential correlations to a number of underlying factors including geography, language as well as cultural, societal, and economic dimensions. Our study is based on a longitudinal (one-year) dataset of daily app popularity from the iOS app stores, covering 154 regions around the world. We reveal that app popularity shows great diversity across the world, while similarities exist among countries that share geographical proximity and linguistic convergence. The differences in app popularity across regions can be further correlated with the cultural model and socioeconomic indices we adopt. On top of the dataset and findings, we implement a prediction task that contributes to app distribution, helping developers choose the right market to distribute and promote their apps. To the best of our knowledge, we are the first to attempt to provide a global understanding of the characteristics of app popularity across the mobile app ecosystem. Our observations can benefit stakeholders in the ecosystem, striving to improve app uptake.

The advent of Large Language Models (LLMs) like ChatGPT has markedly transformed software development, aiding tasks from code generation to issue resolution with their human-like text generation. Nevertheless, the effectiveness of these models greatly depends on the nature of the prompts given by developers. Therefore, this study delves into the DevGPT dataset, a rich collection of developer-ChatGPT dialogues, to unearth the patterns in prompts that lead to effective problem resolutions. The underlying motivation for this research is to enhance the collaboration between human developers and AI tools, thereby improving productivity and problem-solving efficacy in software development. Utilizing a combination of textual analysis and data-driven approaches, this paper seeks to identify the attributes of prompts that are associated with successful interactions, providing crucial insights for the strategic employment of ChatGPT in software engineering environments.

Unlike fungible tokens (e.g., cryptocurrency), a Non-Fungible Token (NFT) is unique and indivisible. As such, they can be used to authenticate ownership of digital assets (e.g., a photo) in a decentralized fashion. Given that NFTs have generated significant media attention since 2021, we perform a large-scale measurement study of the NFT ecosystem. We collect over 242M transfer logs and over 97M marketplace transactions until Aug 1st, 2023, by far the largest NFT dataset, to the best of our knowledge. We characterize the on-chain behavior of NFTs and their trading across five major marketplaces. We find that, although the NFT ecosystem is growing rapidly, it is driven by a relatively small set of dominant centralized players, with suspicious trade activities, e.g., over 23% of the monetary volume is generated by malicious wash trading and the ecosystem has experienced over 157K cases of NFT arbitrage, with a total sum of over \25M profit. Our observations motivate the need for more research efforts in the NFT security analysis.

Web-based trigger-action platforms (TAP) allow users to integrate Internet of Things (IoT) systems and online services into trigger-action integrations (TAIs), facilitating rich automation tasks known as applets. Despite their benefits, these integrations~(typically involving the TAP, trigger, and action service providers) pose significant security and privacy challenges, such as mis-triggering and data leakage. This work investigates cross-entity permission management within TAIs to address the underlying causes of these security and privacy issues, emphasizing permission-functionality consistency to ensure fairness in permission requests. We introduce PFCon, a system that leverages GPT-based language models for analyzing required and requested permissions, revealing excessive permission requests in a large-scale study of IFTTT TAP. Our findings highlight the need for service providers to enforce permission-functionality consistency, raising awareness of the importance of security and privacy in TAI.

The increasing demand for remote work and virtual interactions has heightened the usage of business collaboration platforms~(BCPs), with Google Workspace as a prominent example. These platforms enhance team collaboration by integrating Google Docs, Slides, Calendar, and feature-rich third-party applications (add-ons). However, such integration of multiple users and entities has inadvertently introduced new and complex attack surfaces, elevating security and privacy risks in resource management to unprecedented levels. In this study, we conduct a systematic study on the effectiveness of the cross-entity resource management in Google Workspace, the most popular BCP. Our study unveils the access control enforcement in real-world BCPs for the first time. Based on this, we formulate the attack surfaces inherent in BCPs and conduct a comprehensive assessment, pinpointing three vulnerability types leading to distinct attacks. An analysis of 4,732 marketplace add-ons reveals that approximately 70% are potentially vulnerable to these attacks. We propose robust countermeasures to improve BCP security, urging immediate action and setting a foundation for future research.

As smartphones and mobile apps permeate every aspect of people’s lives, children are accessing mobile devices at an increasingly younger age. The inescapable exposure of advertisements in mobile apps to children has grown alarmingly. Mobile advertisements are placed by advertisers and subsequently distributed by ad SDKs, under the rare control of app developers and app markets’ content ratings. Indeed, content that is objectionable and harmful to children’s mental health has been reported to appear in advertising, such as pornography. However, few studies have yet concentrated on automatically and comprehensively identifying such kid-unsuitable mobile advertising. In this paper, we first characterize the regulations for mobile ads relating to children. We then propose our novel automated dynamic analysis framework, named AdRambler, that attempts to collect ad content throughout the lifespan of mobile ads and identify their inappropriateness for child app users. Using AdRambler, we conduct a large-scale (25,000 mobile apps) empirical investigation and reveal the non-incidental presence of inappropriate ads in apps with child-included target audiences. We collected 11,270 ad views and identified 1,289 ad violations (from 775 apps) of child user regulations, with roughly half of the app promotions not in compliance with host apps’ content ratings. Our finding indicates that even certified ad SDKs could still propagate inappropriate advertisements. We further delve into the question of accountability for the presence of inappropriate advertising and provide concrete suggestions for all stakeholders to take action for the benefit of children.

Online content sharing is a widely used feature in Android apps. In this paper, we observe a new Fake-Share attack that adversaries can abuse existing content sharing services to manipulate the displayed source of shared content to bypass the content review of targeted Online Social Apps (OSAs) and induce users to click on the shared fraudulent content. We show that seven popular content-sharing services (including WeChat, AliPay, and KakaoTalk) are vulnerable to such an attack. To detect this kind of attack and explore whether adversaries have leveraged it in the wild, we propose DeFash, a multi-granularity detection tool including static analysis and dynamic verification. The extensive in-the-lab and in-the-wild experiments demonstrate that DeFash is effective in detecting such attacks. We have identified 51 real-world apps involved in Fake-Share attacks. We have further harvested over 24K Sharing Identification Information (SIIs) that can be abused by attackers. It is hence urgent for our community to take actions to detect and mitigate this kind of attack.

Recent studies have shown the promising direction of deep learning based bug detection, which relieves human experts from the tedious and subjective task of manually summarizing features. Simple one-statement bugs (i.e., SStuBs), which occur relatively often in Java projects, cannot be well spotted by existing static analysis tools. In this paper, we make effort to empirically analyze whether deep learning based techniques could be used to detecting SStuBs. We have re-implemented two state-of-the-art techniques in approximately 3,000 lines of code and adopted them to detecting Java SStuBs. Experiments on large-scale datasets suggest that although deep vulnerability detectors can achieve much better results than existing static analyzers, the SStuBs cannot be well flagged when comparing with traditional complex vulnerabilities. We further look in detail on the per bug category basis, observing that deep learning based methods perform better when detecting some specific types of bugs (e.g., "Same Function Change Caller"), which have strong data flow and control flow semantic. Our observations could offer implications on the automated detection and repair of SStuBs.

Mobile gambling app, as a new type of online gambling service emerging in the mobile era, has become one of the most popular and lucrative underground businesses in the mobile app ecosystem. Since its born, mobile gambling app has received strict regulations from both government authorities and app markets. However, to the best of our knowledge, mobile gambling apps have not been investigated by our research community. In this paper, we take the first step to fill the void. Specifically, we first perform a 5-month dataset collection process to harvest illegal gambling apps in China, where mobile gambling apps are outlawed. We have collected 3,366 unique gambling apps with 5,344 different versions. We then characterize the gambling apps from various perspectives including app distribution channels, network infrastructure, malicious behaviors, abused third-party and payment services. Our work has revealed a number of covert distribution channels, the unique characteristics of gambling apps, and the abused fourth-party payment services. At last, we further propose a “guilt-by-association” expansion method to identify new suspicious gambling services, which help us further identify over 140K suspicious gambling domains and over 57K gambling app candidates. Our study demonstrates the urgency for detecting and regulating illegal gambling apps.

To improve app quality and nip the potential threats in the bud, modern app markets have released strict guidelines along with app vetting process before app publishing. However, there has been growing evidence showing the ineffectiveness of app vetting, making potentially harmful and policy-violation apps sneak into the market from time to time. Therefore, app removal is a common practice, and market maintainers have to remove undesired apps from the market periodically in a reactive manner. Although a number of reports and news media have mentioned removed apps, our research community still lacks the comprehensive understanding of the landscape of this kind of apps. To fill the void, in this paper, we present a large-scale and longitudinal study of removed apps in iOS app store. We first make great efforts to record daily snapshot of iOS app store continuously in a span of 1.5 years. By comparing each two consecutive snapshots, we have collected the information of over 1 million removed apps with their accurate removed date. This comprehensive dataset enables us to characterize the overall landscape of removed apps. We observe that, although most of the removed apps are low-quality apps (e.g., outdated and abandoned), a number of the removed apps are quite popular. We further investigate the practical reasons leading to the removal of such popular apps, and observe several interesting reasons, including ranking fraud, fake description, and content issues, etc. More importantly, most of these mis-behaviors can be reflected on app meta information including app description, app review, and ASO keywords. It motivates us to design an automated approach to flagging the removed apps. Experiment result suggests that, even without accessing to the bytecode of mobile apps, we can identify the removed apps with good performance (F1=83%). Furthermore, we are able to flag the removed apps in advance as long as their inappropriate behaviors appear in their metadata. We believe our approach can work as a whistle blower that pinpoints policy-violation behaviors timely, which will be quite effective in improving the app maintenance process.

One reason for the popularity of Bitcoin is due to its anonymity. Although several heuristics have been used to break the anonymity, new approaches are proposed to enhance its anonymity at the same time. One of them is the mixing service. Unfortunately, mixing services have been abused to facilitate criminal activities, e.g., money laundering. As such, there is an urgent need to systematically understand Bitcoin mixing services.

Domain squatting, the adversarial tactic where attackers register domain names that mimic popular ones, has been observed for decades. However, there has been growing anecdotal evidence that this style of attack has spread to other domains. In this paper, we explore the presence of squatting attacks in the mobile app ecosystem. In “App Squatting”, attackers release apps with identifiers (e.g., app name or package name) that are confusingly similar to those of popular apps or well-known Internet brands. This paper presents the first in-depth measurement study of app squatting showing its prevalence and implications. We first identify 11 common deformation approaches of app squatters and propose “AppCrazy”, a tool for automatically generating variations of app identifiers. We have applied AppCrazy to the top-500 most popular apps in Google Play, generating 224,322 deformation keywords which we then use to test for app squatters on popular markets. Through this, we confirm the scale of the problem, identifying 10,553 squatting apps (an average of over 20 squatting apps for each legitimate one). Our investigation reveals that more than 51% of the squatting apps are malicious, with some being extremely popular (up to 10 million downloads). Meanwhile, we also find that mobile app markets have not been successful in identifying and eliminating squatting apps. Our findings demonstrate the urgency to identify and prevent app squatting abuses. To this end, we have publicly released all the identified squatting apps, as well as our tool AppCrazy.

Advertisement drives the economy of the mobile app ecosystem. As a key component in the mobile ad business model, mobile ad content has been overlooked by the research community, which poses a number of threats, e.g., propagating malware and undesirable contents. To understand the practice of these devious ad behaviors, we perform a large-scale study on the app contents harvested through automated app testing. In this work, we first provide a comprehensive categorization of devious ad contents, including five kinds of behaviors belonging to two categories: ad loading content and ad clicking content. Then, we propose MadDroid, a framework for automated detection of devious ad contents. MadDroid leverages an automated app testing framework with a sophisticated ad view exploration strategy for effectively collecting ad-related network traffic and subsequently extracting ad contents. We then integrate dedicated approaches into the framework to identify devious ad contents. We have applied MadDroid to 40,000 Android apps and found that roughly 6% of apps deliver devious ad contents, e.g., distributing malicious apps that cannot be downloaded via traditional app markets. Experiment results indicate that devious ad contents are prevalent, suggesting that our community should invest more effort into the detection and mitigation of devious ads towards building a trustworthy mobile advertising ecosystem.

A large number of research studies have been focused on detecting Android malware in recent years. As a result, a reliable and large-scale malware dataset is essential to build effective malware classifiers and evaluate the performance of different detection techniques. Although several Android malware benchmarks have been widely used in our research community, these benchmarks face several major limitations. First, most of the existing datasets are outdated and cannot reflect current malware evolution trends. Second, most of them only rely on VirusTotal to label the ground truth of malware, while some anti-virus engines on VirusTotal may not always report reliable results. Third, all of them only contain the apps themselves (apks), while other important app information (e.g., app description, user rating, and app installs) is missing, which greatly limits the usage scenarios of these datasets. In this paper, we have created a reliable Android malware dataset based on Google Play's app maintenance results over several years. We first created four snapshots of Google Play in 2014, 2015, 2017 and 2018 respectively. Then we use VirusTotal to label apps with possible sensitive behaviors, and monitor these apps on Google Play to see whether Google has removed them or not. Based on this approach, we have created a malware dataset containing 9,133 samples that belong to 56 malware families with high confidence. We believe this dataset will boost a series of research studies including Android malware detection and classification, mining apps for anomalies, and app store mining, etc.

The continuing expansion of mobile app ecosystems has attracted lots of efforts from the research community. However, although a large number of research studies have focused on analyzing the corpus of mobile apps and app markets, little is known at a comprehensive level on the evolution of mobile app ecosystems. Because the mobile app ecosystem is continuously evolving over time, understanding the dynamics of app ecosystems could provide unique insights that cannot be achieved through studying a single static snapshot. In this paper, we seek to shed light on the dynamics of mobile app ecosystems. Based on 5.3 million app records (with both app metadata and apks) collected from three snapshots of Google Play over more than three years, we conduct the first study on the evolution of app ecosystems from different aspects. Our results suggest that although the overall ecosystem shows promising progress in regard of app popularity, user ratings, permission usage and privacy policy declaration, there still exists a considerable number of unsolved issues including malicious apps, update issues, third-party tracking threats, improper app promotion behaviors, and spamming/malicious developers. Our study shows that understanding the evolution of mobile app ecosystems can help developers make better decision on developing and releasing apps, provide insights for app markets to identifying misbehaviors, and help mobile users to choose desired apps.

To ensure the quality and trustworthiness of the apps within its app market (i.e., Google Play), Google has released a series of policies to regulate app developers. As a result, policy-violating apps (e.g., malware, low-quality apps, etc.) have been removed by Google Play periodically. In reality, we have found that the number of removed apps are actually much more than what we have expected, as almost half of all the apps have been removed or replaced from Google Play during a two year period from 2015 to 2017. However, despite the significant number of removed apps, there are almost no study on the characterization of these removed apps. To this end, this paper takes the first step to understand why Android apps are removed from Google Play, aiming at observing promising insights for both market maintainers and app developers towards building a better app ecosystem. By leveraging two app sets crawled from Google Play in 2015 (over 1.5 million) and 2017 (over 2.1 million), we have identified a set of over 790K removed apps, which are then thoroughly investigated in various aspects. The experimental results have revealed various interesting findings, as well as insights for future research directions.

With the prevalence of smartphones, app markets such as Apple App Store and Google Play has become the center stage in the mobile app ecosystem, with millions of apps developed by tens of thousands of app developers in each major market. This paper presents a study of the mobile app ecosystem from the perspective of app developers. Based on over one million Android apps and 320,000 developers from Google Play, we analyzed the Android app ecosystem from different aspects. Our analysis shows that while over half of the developers have released only one app in the market, many of them have released hundreds of apps. We classified developers into different groups based on the number of apps they have released, and compared their characteristics. Specially, we have analyzed the group of aggressive developers who have released more than 50 apps, trying to understand how and why they create so many apps. We also investigated the privacy behaviors of app developers, showing that some developers have a habit of producing apps with low privacy ratings. Our study shows that understanding the behavior of mobile developers can be helpful to not only other app developers, but also to app markets and mobile users.

Mobile apps frequently request access to sensitive data, such as location and contacts. Understanding the purpose of why sensitive data is accessed could help improve privacy as well as enable new kinds of access control. In this article, we propose a text mining based method to infer the purpose of sensitive data access by Android apps. The key idea we propose is to extract multiple features from app code and then use those features to train a machine learning classifier for purpose inference. We present the design, implementation, and evaluation of two complementary approaches to infer the purpose of permission use, first using purely static analysis, and then using primarily dynamic analysis. We also discuss the pros and cons of both approaches and the trade-offs involved.

The performance of web browsers has become a major bottleneck when dealing with complex webpages. Many calculation redundancies exist when processing similar webpages, thus it is possible to cache and reuse previously calculated intermediate results to improve web browser performance significantly. In this paper, we propose a similarity-based optimization approach to improve webpage processing performance of web browsers. Through caching and reusing of style properties calculated previously, we are able to eliminate the redundancies caused by processing similar webpages from the same website. We propose a tree-structured architecture to store style properties to facilitate efficient caching and reuse. Experiments on webpages of various websites show that the proposed technique can speed up the webpage loading process by up to 68% and reduce the redundant style calculations by up to 77% for the first visit to a webpage with almost negligible overhead.