A Deep Dive inside DREBIN: An Explorative Analysis beyond Android Malware Detection Scores

in ACM Transactions on Privacy and Security (in press)

Machine learning (ML) advances have been extensively explored for implementing large-scale malware detection. When reported in the literature, performance evaluation of ML-based detectors generally ... [more ▼]

Machine learning (ML) advances have been extensively explored for implementing large-scale malware detection. When reported in the literature, performance evaluation of ML-based detectors generally focuses on highlighting the ratio of samples that are correctly or incorrectly classified, overlooking essential questions on why/how the learned models can be demonstrated as reliable. In the Android ecosystem, several recent studies have highlighted how evaluation setups can carry biases related to datasets or evaluation methodologies. Nevertheless, there is little work attempting to dissect the produced model to provide some understanding of its intrinsic characteristics. In this work, we fill this gap by performing a comprehensive analysis of a state-of-the-art Android Malware detector, namely DREBIN, which constitutes today a key reference in the literature. Our study mainly targets an in-depth understanding of the classifier characteristics in terms of (1) which features actually matter among the hundreds of thousands that DREBIN extracts, (2) whether the high scores of the classifier are dependent on the dataset age, (3) whether DREBIN's explanations are consistent within malware families, etc. Overall, our tentative analysis provides insights into the discriminatory power of the feature set used by DREBIN to detect malware. We expect our findings to bring about a systematisation of knowledge for the community. [less ▲]

JuCify: A Step Towards Android Code Unification for Enhanced Static Analysis

in 44th International Conference on Software Engineering (ICSE 2022) (2022, May 21)

Native code is now commonplace within Android app packages where it co-exists and interacts with Dex bytecode through the Java Native Interface to deliver rich app functionalities. Yet, state-of-the-art ... [more ▼]

Native code is now commonplace within Android app packages where it co-exists and interacts with Dex bytecode through the Java Native Interface to deliver rich app functionalities. Yet, state-of-the-art static analysis approaches have mostly overlooked the presence of such native code, which, however, may implement some key sensitive, or even malicious, parts of the app behavior. This limitation of the state of the art is a severe threat to validity in a large range of static analyses that do not have a complete view of the executable code in apps. To address this issue, we propose a new advance in the ambitious research direction of building a unified model of all code in Android apps. The JuCify approach presented in this paper is a significant step towards such a model, where we extract and merge call graphs of native code and bytecode to make the final model readily-usable by a common Android analysis framework: in our implementation, JuCify builds on the Soot internal intermediate representation. We performed empirical investigations to highlight how, without the unified model, a significant amount of Java methods called from the native code are ``unreachable'' in apps' call-graphs, both in goodware and malware. Using JuCify, we were able to enable static analyzers to reveal cases where malware relied on native code to hide invocation of payment library code or of other sensitive code in the Android framework. Additionally, JuCify's model enables state-of-the-art tools to achieve better precision and recall in detecting data leaks through native code. Finally, we show that by using JuCify we can find sensitive data leaks that pass through native code. [less ▲]

A First Look at Security Risks of Android TV Apps

in A First Look at Security Risks of Android TV Apps (2021, November 15)

In this paper, we present to the community the first preliminary study on the security risks of Android TV apps. To the best of our knowledge, despite the fact that various efforts have been put into ... [more ▼]

In this paper, we present to the community the first preliminary study on the security risks of Android TV apps. To the best of our knowledge, despite the fact that various efforts have been put into analyzing Android apps, our community has not explored TV versions of Android apps. There is hence no publicly available dataset containing Android TV apps. To this end, We start by collecting a large set of Android TV apps from the official Google Play store. We then experimentally look at those apps from four security aspects: VirusTotal scans, requested permissions, security flaws, and privacy leaks. Our experimental results reveal that, similar to that of Android smartphone apps, Android TV apps can also come with different security issues. We hence argue that our community should pay more attention to analyze Android TV apps. [less ▲]

ANCHOR: locating android framework-specific crashing faults

in Automated Software Engineering (2021)

Android framework-specific app crashes are hard to debug. Indeed, the callback-based event-driven mechanism of Android challenges crash localization techniques that are developed for traditional Java ... [more ▼]

Android framework-specific app crashes are hard to debug. Indeed, the callback-based event-driven mechanism of Android challenges crash localization techniques that are developed for traditional Java programs. The key challenge stems from the fact that the buggy code location may not even be listed within the stack trace. For example, our empirical study on 500 framework-specific crashes from an open benchmark has revealed that 37 percent of the crash types are related to bugs that are outside the stack traces. Moreover, Android programs are a mixture of code and extra-code artifacts such as the Manifest file. The fact that any artifact can lead to failures in the app execution creates the need to position the localization target beyond the code realm. In this paper, we propose Anchor, a two-phase suspicious bug location suggestion tool. Anchor specializes in finding crash-inducing bugs outside the stack trace. Anchor is lightweight and source code independent since it only requires the crash message and the apk file to locate the fault. Experimental results, collected via cross-validation and in-the- wild dataset evaluation, show that Anchor is effective in locating Android framework-specific crashing faults. [less ▲]

Revisiting Test Cases to Boost Generate-and-Validate Program Repair

in IEEE International Conference on Software Maintenance and Evolution (ICSME) (2021, September)

Taming Reflection: An Essential Step Toward Whole-program Analysis of Android Apps

in ACM Transactions on Software Engineering and Methodology (2021), 30(3), 1-36

Android developers heavily use reflection in their apps for legitimate reasons. However, reflection is also significantly used for hiding malicious actions. Unfortunately, current state-of-the-art static ... [more ▼]

Android developers heavily use reflection in their apps for legitimate reasons. However, reflection is also significantly used for hiding malicious actions. Unfortunately, current state-of-the-art static analysis tools for Android are challenged by the presence of reflective calls which they usually ignore. Thus, the results of their security analysis, e.g., for private data leaks, are incomplete, given the measures taken by malware writers to elude static detection. We propose a new instrumentation-based approach to address this issue in a non-invasive way. Specifically, we introduce to the community a prototype tool called DroidRA, which reduces the resolution of reflective calls to a composite constant propagation problem and then leverages the COAL solver to infer the values of reflection targets. After that, it automatically instruments the app to replace reflective calls with their corresponding Java calls in a traditional paradigm. Our approach augments an app so that it can be more effectively statically analyzable, including by such static analyzers that are not reflection-aware. We evaluate DroidRA on benchmark apps as well as on real-world apps, and demonstrate that it can indeed infer the target values of reflective calls and subsequently allow state-of-the-art tools to provide more sound and complete analysis results. [less ▲]

Les dangers de pastebin

Article for general public (2021)

A Comparison of Pre-Trained Language Models for Multi-Class Text Classification in the Financial Domain

in Companion Proceedings of the Web Conference 2021 (WWW '21 Companion), April 19--23, 2021, Ljubljana, Slovenia (2021, April 19)

A critical review on the evaluation of automated program repair systems

in Journal of Systems and Software (2021)

Lessons Learnt on Reproducibility in Machine Learning Based Android Malware Detection

in Empirical Software Engineering (2021), 26

A well-known curse of computer security research is that it often produces systems that, while technically sound, fail operationally. To overcome this curse, the community generally seeks to assess ... [more ▼]

A well-known curse of computer security research is that it often produces systems that, while technically sound, fail operationally. To overcome this curse, the community generally seeks to assess proposed systems under a variety of settings in order to make explicit every potential bias. In this respect, recently, research achievements on machine learning based malware detection are being considered for thorough evaluation by the community. Such an effort of comprehensive evaluation supposes first and foremost the possibility to perform an independent reproduction study in order to sharpen evaluations presented by approaches’ authors. The question Can published approaches actually be reproduced? thus becomes paramount despite the little interest such mundane and practical aspects seem to attract in the malware detection field. In this paper, we attempt a complete reproduction of five Android Malware Detectors from the literature and discuss to what extent they are “reproducible”. Notably, we provide insights on the implications around the guesswork that may be required to finalise a working implementation. Finally, we discuss how barriers to reproduction could be lifted, and how the malware detection field would benefit from stronger reproducibility standards—like many various fields already have. [less ▲]