Another malware which written in Java, basically it's uses cmd extension commands for example attrib, diskpart etc. If you want to make something most annoyning in Java, it's best nerd guy(s) example.
These are commands which used by this attrib, diskpart, takeown, icacls, del (Based on MS-DOS / Command Prompt), mountvol. To overwrite a disk area, imagine writing a new file on a disk (it not require admin priviledge except C and protected drive). For info at worker.java
https://www.youtube.com/watch?v=rQom5E_aIvE
They are internal worker or simply they are calling like a function when user need them. Decompilation level beginner, it's easy to decompile it. Just extract classes from binary and seperate packages and classes.