  Recently Edge Computing paradigm has gained significant popularity both in
industry and academia. With its increased usage in real-life scenarios,
security, privacy and integrity of data in such environments have become
critical. Malicious deletion of mission-critical data due to ransomware,
trojans and viruses has been a huge menace and recovering such lost data is an
active field of research. As most of Edge computing devices have compute and
storage limitations, difficult constraints arise in providing an optimal scheme
for data protection. These devices mostly use Linux/Unix based operating
systems. Hence, this work focuses on extending the Ext4 file system to APEX
(Adaptive Ext4): a file system based on novel on-the-fly learning model that
provides an Adaptive Recover-ability Aware file allocation platform for
efficient post-deletion data recovery and therefore maintaining data integrity.
Our recovery model and its lightweight implementation allow significant
improvement in recover-ability of lost data with lower compute, space, time,
and cost overheads compared to other methods. We demonstrate the effectiveness
of APEX through a case study of overwriting surveillance videos by CryPy
malware on Raspberry-Pi based Edge deployment and show 678% and 32% higher
recovery than Ext4 and current state-of-the-art File Systems. We also evaluate
the overhead characteristics and experimentally show that they are lower than
other related works.
