Hey there, I'm Tony from Overwolf.
Although MrsHappyPenguin summed up pretty accurately (which makes us happy, thank you penguin! :) ),
I'd like to share some notes for the topic.
First, like MrsHappyPenguin said, Overwolf does inject an overlay which works differently from cross shaders.
Second, Overwolf is approved and will not get you banned. If you'd like to read why, please visit: https://medium.com/overwolf/is-overwolf-going-to-get-me-banned-1ae8a666f66d
TL;DR
As avid gamers ourselves, we are working closely with game publishers to ensure that every app we publish is aligned with their ToS and their 3rd party policies.
Thanks for the read
Game on!
Tony from Overwolf