Caught in the crossfire Vs Overwhelm

If either (or both) of the units you use this on have overwhelm, would excess damage go to the opponents base?

I think the answer is no, because the units are dealing damage rather than attacking, is that correct?

If either (or both) of the units you use this on have overwhelm, would excess damage go to the opponents base?

I think the answer is no, because the units are dealing damage rather than attacking, is that correct?