Evaluating the Reliability of Android Userland Memory Forensics

Abstract

Memory Forensics is one of the most important emerging areas in computer forensics. In memory forensics, analysis of userland memory is a technique that analyses per-process runtime data structures and extracts significant evidence for application-specific investigations. In this research, our focus is to examine the critical challenges faced by process memory acquisition that can impact object and data recovery. Particularly, this research work seeks to address the issues of consistency and reliability in userland memory forensics on Android. In real-world investigations, memory acquisition tools record the information when the device is running. In such scenarios, each application’s memory content may be in flux due to updates that are in progress, garbage collection activities, changes in process states, etc. In this paper we focus on various runtime activities such as garbage collection and process states and the impact they have on object recovery in userland memory forensics. The outcome of the research objective is to assess the reliability of Android userland memory forensic tools by providing new research directions for efficiently developing a metric study to measure the reliability. We evaluated our research objective by analysing memory dumps acquired from 30 apps in different Process Acquisition Modes. The Process Acquisition Mode (PAM) is the memory dump of a process that is extracted while external runtime factors are triggered. Our research identified an inconsistency in the number of objects recovered from analysing the process memory dumps with runtime factors included. Particularly, the evaluation results revealed differences in the count of objects recovered in different acquisition modes. We utilized Euclidean distance and covariance as the metrics for our study. These two metrics enabled the authors to identify how the change in the number of recovered objects in PAM impact forensic analysis. Our conclusion revealed that runtime factors could on average result in about 20% data loss, thus revealing these factors can have an obvious impact on object recovery.