Digital forensic analysis of the private mode of browsers on Android

The smartphone has become an essential electronic device in our daily lives. We carry our most precious and important data on it, from family videos of the last few years to credit card information so that we can pay with our phones. In addition, in recent years, mobile devices have become the preferred device for surfing the web, already representing more than 50% of Internet traffic. As one of the devices we spend the most time with throughout the day, it is not surprising that we are increasingly demanding a higher level of privacy. One of the measures introduced to help us protect our data by isolating certain activities on the Internet is the private mode integrated in most modern browsers. Of course, this feature is not new, and has been available on desktop platforms for more than a decade. Reviewing the literature, one can find several studies that test the correct functioning of the private mode on the desktop. However, the number of studies conducted on mobile devices is incredibly small. And not only is it small, but also most of them perform the tests using various emulators or virtual machines running obsolete versions of Android. Therefore, in this paper we apply the methodology we presented in a previous work to Google Chrome, Brave, Mozilla Firefox, and Tor Browser running on a tablet with Android 13 and on two virtual devices created with Android Emulator. The results confirm that these browsers do not store information about the browsing performed in private mode in the file system. However, the analysis of the volatile memory made it possible to recover the username and password used to log in to a website or the keywords typed in a search engine, even after the devices had been rebooted.