When the Guard failed the Droid: A case study of Android malware

TL;DR

This paper demonstrates that Android malware detection systems built on the open-source Androguard library are highly vulnerable to evasion attacks, which can significantly reduce detection rates and require comprehensive evaluation of manipulated apps.

Contribution

It introduces innovative evasion attacks targeting Android malware detection systems and proposes a novel evaluation scheme considering both maliciousness and functionality of manipulated apps.

Findings

Detection rates drop to 0% after evasion attacks

Evasion attacks can produce non-functional malicious apps

Assessment of evasion attacks should include functionality and maliciousness

Abstract

Android malware is a persistent threat to billions of users around the world. As a countermeasure, Android malware detection systems are occasionally implemented. However, these systems are often vulnerable to \emph{evasion attacks}, in which an adversary manipulates malicious instances so that they are misidentified as benign. In this paper, we launch various innovative evasion attacks against several Android malware detection systems. The vulnerability inherent to all of these systems is that they are part of Androguard~\cite{desnos2011androguard}, a popular open source library used in Android malware detection systems. Some of the detection systems decrease to a 0\% detection rate after the attack. Therefore, the use of open source libraries in malware detection systems calls for caution. In addition, we present a novel evaluation scheme for evasion attack generation that exploits the weak spots of known Android malware detection systems. In so doing, we evaluate the functionality and maliciousness of the manipulated instances created by our evasion attacks. We found variations in both the maliciousness and functionality tests of our manipulated apps. We show that non-functional apps, while considered malicious, do not threaten users and are thus useless from an attacker's point of view. We conclude that evasion attacks must be assessed for both functionality and maliciousness to evaluate their impact, a step which is far from commonplace today.