Cornell held a slim 27-25 lead at the half but pumped the margin to 48-34 at the 12:49 mark on Hatter's flurry and JoJo Fallas' 3-point jumper. The Big Red coasted home from there.
Hatter connected on 5 of 10 from long range and nailed three from beyond the arc to start the second half.
Cornell (5-4) remained undefeated at home by making 10 of 21 3-point attempts on 24-of-48 shooting.
The River Hawks were held to 21 of 53 from the field (39.6 percent) and saw their six-game win streak snapped.