Memento Ransomware is a python based "utility" that use legitimate WinRAR to do its bidding. It copies its victims files in an Password protected archive and delete the original file.
Polaris ransomware encrypts user data and ask user to contact them on Discord channel for ransom negotiations. It actively targeting Linux servers.
Chaos Ransomware encrypts user files with AES and RSA and demands 2000 yen roughly ~$17 in pre paid cards. It is currently focused on Japan and spread via Minecraft Gamers Alts.
DECAF is a Golang based ransomware. It is written in golang 1.17 in which a new complex mechanism of parameter passing to a function is adopted. This protect it form reserve engineering more difficult.
Karma Ransomware is next evolutionary step in the development of Nemty Ransomware.