What should I do with a master student's online report that made my work look like his?
Ignore it. There are lots of bad papers out there that will never be noticed and/or cited -- and given the title, everyone who happens to come across it will realize that the original source is your paper.

Spare your worries for the important questions in life, for example on writing the follow-up paper that clearly explains why the original paper you wrote is so important!