Fileless malware and cryptojacking attacks have appeared independently as the new alarming threats in 2017. After 2020, fileless attacks have been devastating for victim organizations with low-observable characteristics. Also, the amount of unauthorized cryptocurrency mining has increased after 2019. Adversaries have started to merge these two different cyberattacks to gain more invisibility and profit under "Fileless Cryptojacking." This paper aims to provide a literature review in academic papers and industry reports for this new threat. Additionally, we present a new threat hunting-oriented DFIR approach with the best practices derived from field experience as well as the literature. Last, this paper reviews the fundamentals of the fileless threat that can also help ransomware researchers examine similar patterns.