Using standards proposed in another paper
There is nothing wrong with adopting standards from previous work into your work. In fact it is very common. Research is an iterative process and that's a good thing. You don't want to reinvent the wheel every time you want to test a new car engine.

If you did not measure DDoS attacks using the technique from this paper, you would end up measuring using a technique from another paper. Even if you invented your own measuring technique, you would want to publish a comparison of it with techniques established in the literature.

As the comments have said, you should cite the previous paper and give a brief overview of their technique. If the technique is not well known or complicated, you may want to devote more ink to explaining it, but a small paragraph should really suffice. People won't be reading your work to learn about the other paper, they're reading it to see what you've done. If they're interested in the other paper, they'll go read that.