Are free Android app security analysis tools effective in detecting known vulnerabilities?

In recent years, with the growing popularity of smartphones, the number of Android malware shows explosive growth. As malicious apps may steal users' sensitive data and money from mobile and bank accounts, it's important to detect potential malicious behavior in real time. To achieve this goal, we propose a dynamic behavior inspection and analysis framework for malicious behavior detection in Android apps. A customized Android system is built to record apps' API (Application Programming Interface) calls, permission uses, and some other runtime features such as user operations. We also develop an automated testing platform to test massive samples so as to collect dynamic app behavior records. Then we exploit these records to extract apps' runtime features of both user interaction and app dynamic behavior for benign and malicious behavior classification. The experimental results show that the app behavior classification can reach an accuracy of 99.0%, identifying 71.8% instances of malware samples by running each app for only 18 minutes.

Ethereum smart contracts are programs that run on the Ethereum blockchain, and many smart contract vulnerabilities have been discovered in the past decade. Many security analysis tools have been created to detect such vulnerabilities, but their performance decreases drastically when codes to be analyzed are being rewritten. In this paper, we propose Eth2Vec, a machine-learning-based static analysis tool for vulnerability detection, with robustness against code rewrites in smart contracts. Existing machine-learning-based static analysis tools for vulnerability detection need features, which analysts create manually, as inputs. In contrast, Eth2Vec automatically learns features of vulnerable Ethereum Virtual Machine (EVM) bytecodes with tacit knowledge through a neural network for language processing. Therefore, Eth2Vec can detect vulnerabilities in smart contracts by comparing the code similarity between target EVM bytecodes and the EVM bytecodes it already learned. We conducted experiments with existing open databases, such as Etherscan, and our results show that Eth2Vec outperforms the existing work in terms of well-known metrics, i.e., precision, recall, and F1-score. Moreover, Eth2Vec can detect vulnerabilities even in rewritten codes.

A large-scale study on the adoption of anti-debugging and anti-tampering protections in android apps

Most of today's mobile apps rely on the underlying networks to deliver key functions such as web browsing, file synchronization, and social networking. Compared to desktop-based networks, mobile networks are much more dynamic with frequent connectivity disruptions, network type switches, and quality changes, posing unique programming challenges for mobile app developers. As revealed in this paper, many mobile app developers fail to handle these intermittent network conditions in the mobile network programming. Consequently, network programming defects (NPDs) are pervasive in mobile apps, causing bad user experiences such as crashes, data loss, etc. Despite the development of network libraries in the hope of lifting the developers' burden, we observe that many app developers fail to use these libraries properly and still introduce NPDs. In this paper, we study the characteristics of the real-world NPDs in Android apps towards a deep understanding of their impacts, root causes, and code patterns. Driven by the study, we build NChecker, a practical tool to detect NPDs by statically analyzing Android app binaries. NChecker has been applied to hundreds of real Android apps and detected 4180 NPDs from 285 randomly-selected apps with a 94+% accuracy. Our further analysis of these defects reveals the common mistakes of app developers in working with the existing network libraries' abstractions, which provide insights for improving the usability of mobile network libraries.

Android apps often have a “dark mode” option used in low-light situations, for those who find the conventional color palette problematic, or because of personal preferences. Typically developers add a dark mode option for their apps with different backgrounds, text, and sometimes iconic forms. We wanted to understand the actual provision of this dark mode in real-world Android apps through an empirical study of posts from Stack Overflow and real-world Android app analysis. Using these approaches, we identified the aspects of dark mode that developers implemented as well as the key difficulties they experienced in implementing it. We performed a quantitative analysis using open-coding of more than 300 discussion threads to create a taxonomy regarding the aspects discussed by developers with respect to dark mode in Android. Our quantitative analysis of over 6,000 Android apps highlights which dark mode features are typically provided in Android apps and which aspects developers care about during dark mode design. We also examined four app development support tools to see how well they aid Android app development for dark mode. From our analysis, we distilled some key lessons to guide further research and actions in aiding developers with supporting users who require such assistive features. For example, developers should be aware of the potential risks in using unsuitable dark mode design schema and researchers should take dark mode features into consideration when developing app development support tools.

Software Engineering (SE) communities such as Stack Overflow have become unwelcoming, particularly through members' use of offensive language. Research has shown that offensive language drives users away from active engagement within these platforms. This work aims to explore this issue more broadly by investigating the nature of offensive language in comments posted by users in four prominent SE platforms - GitHub, Gitter, Slack and Stack Overflow (SO). It proposes an approach to detect and classify offensive language in SE communities by adopting natural language processing and deep learning techniques. Further, a Conflict Reduction System (CRS), which identifies offence and then suggests what changes could be made to minimize offence has been proposed. Beyond showing the prevalence of offensive language in over 1 million comments from four different communities which ranges from 0.07% to 0.43%, our results show promise in successful detection and classification of such language. The CRS system has the potential to drastically reduce manual moderation efforts to detect and reduce offence in SE communities.

Case study describing the pillars, personnel, and process of developing the TARDIS:REFLUX smartphone app

Android apps include third-party native libraries to increase performance and to reuse functionality. Native code is directly executed from apps through the Java Native Interface or the Android Native Development Kit. Android developers add precompiled native libraries to their projects, enabling their use. Unfortunately, developers often struggle or simply neglect to update these libraries in a timely manner. This results in the continuous use of outdated native libraries with unpatched security vulnerabilities years after patches became available. To further understand such phenomena, we study the security updates in native libraries in the most popular 200 free apps on Google Play from Sept. 2013 to May 2020. A core difficulty we face in this study is the identification of libraries and their versions. Developers often rename or modify libraries, making their identification challenging. We create an approach called LibRARIAN (LibRAry veRsion IdentificAtioN) that accurately identifies native libraries and their versions as found in Android apps based on our novel similarity metric bin2sim. LibRARIAN leverages different features extracted from libraries based on their metadata and identifying strings in read-only sections. We discovered 53/200 popular apps (26.5%) with vulnerable versions with known CVEs between Sept. 2013 and May 2020, with 14 of those apps remaining vulnerable. We find that app developers took, on average, 528.71 ±40.20 days to apply security patches, while library developers release a security patch after 54.59 ± 8.12 days---a 10 times slower rate of update.

WebView is a widely used Android component that augments a native app with web browser capabilities. It eases the interactions between an app's native code and web code. However, the interaction mechanism of WebView induces new types of bugs in Android apps. Understanding the characteristics and manifestation of these WebView-induced bugs ( $\omega \text{Bugs}$ for short) facilitates the correct usages of WebViews in Android apps. This motivates us to conduct the first empirical study on $\omega \text{Bugs}$ based on those found in popular open-source Android apps. Our study identified the major root causes and consequences of $\omega \text{Bugs}$ and made interesting observations that can be leveraged for detecting and diagnosing $\omega \text{Bugs}$ . Based on the empirical study, we further propose an automated testing technique $\omega \text{Droid}$ to effectively expose $\omega \text{Bugs}$ in Android apps. In our experiments, $\omega \text{Droid}$ successfully discovered 30 unique and previously-unknown $\omega \text{Bugs}$ when applied to 146 open-source Android apps. We reported the 30 $\omega \text{Bugs}$ to the corresponding app developers. Out of these 30 $\omega \text{Bugs}$ , 14 were confirmed and 7 of them were fixed. This shows that $\omega \text{Droid}$ can effectively detect $\omega \text{Bugs}$ that are of the developers' concern.

The android platform adopts permissions to protect sensitive resources from untrusted apps. However, after permissions are granted by users at install time, apps could use these permissions (sensitive resources) with no further restrictions. Thus, recent years have witnessed the explosion of undesirable behaviors in Android apps. An important part in the defense is the accurate analysis of Android apps. However, traditional syscall-based analysis techniques are not well-suited for Android, because they could not capture critical interactions between the application and the Android system. This paper presents VetDroid, a dynamic analysis platform for generally analyzing sensitive behaviors in Android apps from a novel permission use perspective. VetDroid proposes a systematic permission use analysis technique to effectively construct permission use behaviors, i.e., how applications use permissions to access (sensitive) system resources, and how these acquired permission-sensitive resources are further utilized by the application. With permission use behaviors, security analysts can easily examine the internal sensitive behaviors of an app. Using real-world Android malware, we show that VetDroid can clearly reconstruct fine-grained malicious behaviors to ease malware analysis. We further apply VetDroid to 1249 top free apps in Google Play. VetDroid can assist in finding more information leaks than TaintDroid, a state-of-the-art technique. In addition, we show how we can use VetDroid to analyze fine-grained causes of information leaks that TaintDroid cannot reveal. Finally, we show that VetDroid can help to identify subtle vulnerabilities in some (top free) applications otherwise hard to detect.

The drastic increase of mobile apps and its direct impact on the security of user's device and data cannot be neglected. Such data nowadays is related to (almost) all life aspects. Even with the growing awareness to develop more secure apps, but still existed mobile apps found on app stores cannot be considered fully benign. This paper is giving a special attention to Android permissions and how they can be abused by security attacks. Most rated education apps have been selected to perform deep permissions analysis and categorization in terms of protection level and mostly abused ones. Moreover, the apps have been examined to check if they support advertisements or not. The results reveal that 80.3% of the apps are requesting permissions more than what they need and actually used. Consequently, such over-privileged apps would be exposed to serious malicious behaviors. The paper discusses possible solutions to overcome this issue and suggests possible ways to select the required permissions throughout the app development process.

Android apps must work correctly even if their execution is interrupted by external events. For instance, an app must work properly even if a phone call is received, or after its layout is redrawn because the smartphone has been rotated. Since these events may require destroying, when the execution is interrupted, and recreating, when the execution is resumed, the foreground activity of the app, the only way to prevent the loss of state information is saving and restoring it. This behavior must be explicitly implemented by app developers, who often miss to implement it properly, releasing apps affected by data loss problems, that is, apps that may lose state information when their execution is interrupted. Although several techniques can be used to automatically generate test cases for Android apps, the obtained test cases seldom include the interactions and the checks necessary to exercise and reveal data loss faults. To address this problem, this paper presents Data Loss Detector (DLD), a test case generation technique that integrates an exploration strategy, data-loss-revealing actions, and two customized oracle strategies for the detection of data loss failures. DLD has been able to reveal 75% of the faults in a benchmark of 54 Android app releases affected by 110 known data loss faults. DLD also revealed unknown data loss problems, outperforming competing approaches.

Mobile push notifications have been widely used in mobile platforms to deliver all sorts of information to app users. Although it offers great convenience for both app developers and mobile users, this feature was frequently reported to serve malicious and aggressive purposes, such as delivering annoying push notification advertisement. However, to the best of our knowledge, this problem has not been studied by our research community so far. To fill the void, this paper presents the first study to detect aggressive push notifications and further characterize them in the global mobile app ecosystem on a large scale. To this end, we first provide a taxonomy of mobile push notifications and identify the aggressive ones using a crowdsourcing-based method. Then we propose sc DaPanda, a novel hybrid approach, aiming at automatically detecting aggressive push notifications in Android apps. sc DaPanda leverages a guided testing approach to systematically trigger and record push notifications. By instrumenting the Android framework, sc DaPanda further collects all notification-relevant runtime information to flag the aggressive ones. Our experimental results show that sc DaPanda is capable of detecting different types of aggressive push notifications effectively in an automated way. By applying sc DaPanda to 20,000 Android apps from different app markets, it yields over 1,000 aggressive notifications, which have been further confirmed as true positives. Our in-depth analysis further reveals that aggressive notifications are prevalent across different markets and could be manifested in all the phases in the lifecycle of push notifications. It is hence urgent for our community to take actions to detect and mitigate apps involving aggressive push notifications.

Android apps are developed using a Software Development Kit (SDK), where the Android application programming interface (API) enables app developers to harness the functionalities of Android devices by interacting with services and hardware. However, API frequently evolves together with its associated SDK. The mismatch between the API level supported by the device where apps are installed and the API level targeted by app developers can induce compatibility issues. These issues can manifest themselves as unexpected behaviors, including runtime crashes, creating a poor user experience. Recent studies investigated API evolution to ensure the reliability of the Android apps, however, they require improvements. This work aims to establish novel methodologies that will improve the state-of-the-art compatibility issue detection and testing approaches.

It has been reported in the literature that about twenty new software vulnerabilities are reported weekly. This situation has increased the security awareness in the software community. Nowadays, software services are expected not only to satisfy functional requirements but also to resist malicious attacks. As demand for more trustworthy systems is increasing, the software industry is adjusting itself to security standards and practices by increasing security assessment and testing effort. Even though there is a consensus that better software engineering is to improve software quality in the early stage of software development, so far, various approaches that have been proposed to analyze and quantitatively measure the software security target, primarily show the finished software products in their operational life. There are few achievements on how to reduce or effectively mitigate the security risks faced by software products during the development process. In this chapter, the authors introduce a novel model-driven perspective on secure software engineering, which integrates seamlessly software security analysis with traditional software development activities. A systematic security engineering process that starts in the early stages of the software development process and spans the entire software lifecycle is presented. Fundamental software security concepts and analysis techniques are also introduced, and several illustrative examples are presented, with focus on security requirements and risk analysis.