Authors: Dennis Wijnberg (National Police of the Netherlands) and Nhien-An Le-Khac (University College Dublin)
DFRWS APAC 2021
Abstract
On a daily basis, law enforcement officers struggle with suspects using mobile communication applications for criminal activities. These mobile applications replaced SMS-messaging and evolved the last few years from plain-text data transmission and storage to an encrypted version. Regardless of the benefits for all law abiding citizens, this is considered to be the downside for criminal investigations. Normal smartphone, computer or network investigations do no longer provide the contents of the communication in real-time when suspects are using apps like WhatsApp, Signal or Telegram. Among them, WhatsApp is one of the most common smartphone applications for communication, both criminal as well as legal activities. At the beginning, WhatsApp communication between smartphone and server used to be in plain-text and therefore visible to law enforcement during a wiretap. Early 2016 WhatsApp introduced end-to-end encryption for all users, immediately keeping law enforcement officers around the world in the dark. Existing research to recuperate the position of law enforcement is limited to a single field of investigation and often limited to post mortem research on smartphone or computer while wiretapping is limited to metadata information. Therefore, it provides only historical data or metadata while law enforcement officers want a continuous stream of live and substantive information. This paper identified that gap in available scenarios for law enforcement investigations and identified a gap in methods available for forensic acquiring and processing these scenarios. In this paper, we propose a forensic approach to create real-time insight in the WhatsApp communication. Our approach is based on the wiretapping, decrypting WhatsApp databases, open source intelligence and WhatsApp Web communication analysis. We also evaluate our method with different scenarios in WhatsApp forensics to prove its feasibility and efficiency. Through these scenarios, we found that by providing real-time intelligence such as profile pictures, their activity, voice and video call behaviour including location data as well as remote access to a suspect WhatsApp account, their conversations including voice messages, (live) geolocation, shared contacts, documents, images and videos are made accessible. Hence, our corresponding method can be used by law enforcement agencies around the world to reinforce their position in the world of WhatsApp communication interception.