Hackers are targeting banks, telecommunication companies, government organizations in 40 countries, including the US, South America, Europe and Africa. Fileless malware is a piece of nasty software that does not copy any files or folder to the hard drive in order to get executed. Since the malware runs in the memory, the memory acquisition becomes useless once the system gets rebooted, making it difficult for digital forensic experts to find traces of the malware. The ultimate goal of the attackers was apparently aimed at compromising computers that control ATMs so that they could steal money.
Source: https://thehackernews.com/2017/02/fileless-malware-bank.html