The incident took place at roughly 7 p.m. on Sept. 25 inside the stadium's Great Hall, a 31,000-square-foot area lined with banners of famous Yankees.
The suspect, described as a man in his 30s who is about 5 feet 7 inches tall, went up to his 23-year-old victim, grabbed her butt and fled, police said.
The unidentified suspect was a guest in one of the stadium's boxes and frequently goes to Milton, N.J., according to the NYPD.
Anyone with information about this incident is asked to call the NYPD's Crime Stoppers Hotline at 800-577-TIPS. The public can also submit their tips by logging onto the Crime Stoppers Website at www.nypdcrimestoppers.com or texting their tips to 274637(CRIMES), then entering TIP577.