Two java programs: Master controller (commander) and Slave server (zombie). It was created in 2009 as a side project when studying the network programming courser ieg4180: https://course.ie.cuhk.edu.hk/~ierg4180/
The 'slave' server open a port and take command from the master controller, it could trigger ball scratching dos attack on slaves and at most consume 256mb on the zombie by default setting under java sandbox as I remember...
Nothing critical.