https://www.bleepingcomputer.com/news/security/ratel-rat-targets-outdated-android-phones-in-ransomware-attacks/

An open-source Android malware named 'Ratel RAT' is widely deployed by multiple cybercriminals to attack outdated devices, some aiming to lock them down with a ransomware module that demands payment on Telegram.

Researchers Antonis Terefos and Bohdan Melnykov at Check Point report detecting over 120 campaigns using the Rafel RAT malware.