MTDroid: A Moving Target Defense-Based Android Malware Detector Against Evasion Attacks

Machine learning (ML) has been widely adopted for Android malware detection to deal with serious threats brought by explosive malware attacks. However, it has been recently proven that ML-based detection systems exhibit inherent vulnerabilities to evasion attacks, which inject adversarial perturbations into a malicious app to hide its malicious behaviors and evade detection. To date, researchers have not found effective solutions for this critical problem. Although there are some similar works in the image classification field, most of those ideas cannot be borrowed due to the significant differences between images and Android apps. In this paper, we exploit Moving Target Defense (MTD) to continually change the attack surface of the protected detector and create uncertainty on the attacker side. We thus propose a novel Android malware detection framework named MTDroid, which fully leverages a seamless blend of dynamicity, diversity, and heterogeneity to mitigate the impact of evasion attacks. To this end, we develop a dynamic model pool to decrease the exposure time of a single classifier, by building and rebuilding multiple heterogeneous models with distinct data. We then generate diversified variant models to provide defensive measures against various attacks, and further improve robustness through ensemble learning. Specifically, we propose a two-stage selection algorithm to optimize the ensemble learning process, and design a hybrid update strategy to refresh the framework dynamically. The experimental results show that MTDroid significantly enhances the robustness against a wide range of attacks and outperforms the state-of-the-art methods upon three popular practical datasets.