Authorities say the suspect followed the woman along East 149th Street down Jackson Avenue in Mott Haven around 2 a.m. Saturday and flashed the box cutter when they reached St. Mary's Park.
He then pulled on the woman's shirt, reached under her clothes and pushed her to the ground. He climbed on top of her and she screamed for help. Then he ran off.
Police released surveillance video (above) of the suspect walking down the sidewalk.
Anyone with information about the attack is asked to call Crime Stoppers at 1-800-577-TIPS.