Breaking into the vault: Privacy, security and forensic analysis of Android vault applications

摘要

In this work we share the first account for the forensic analysis, security and privacy of Android vault applications. Vaults are designed to be privacy enhancing as they allow users to hide personal data but may also be misused to hide incriminating files. Our work has already helped law enforcement in the state of Connecticut to reconstruct 66 incriminating images and 18 videos in a single criminal case. We present case studies and results from analyzing 18 Android vault applications (accounting for nearly 220 million downloads from the Google Play store) by reverse engineering them and examining the forensic artifacts they produce. Our results showed that 12/18 obfuscated their code and 5/18 applications used native libraries hindering the reverse engineering process of these applications. However, we still recovered data from the applications without root access to the Android device as we were able to ascertain hidden data on the device without rooting for 10/18 of the applications. 6/18 of the vault applications were found to not encrypt photos they stored, and 8/18 were found to not encrypt videos. 7/18 of the applications were found to store passwords in cleartext. We were able to also implement a swap attack on 5/18 applications where we achieved unauthorized access to the data by swapping the files that contained the password with a self-created one. In some cases, our findings illustrate unfavorable security implementations of privacy enhancing applications, but also showcase practical mechanisms for investigators to gain access to data of evidentiary value. In essence, we broke into the vaults.