The victim was attacked as she walked her dog around 10:45 a.m., police say.
The attacker walked up behind the victim and forced her between two garages near 52nd Street and Berkeley Avenue.
The attacker is described as 35-40 years old, 6'2"-6'4", medium to slim build with short black hair, brown eyes, no facial hair, dark complexion, and wearing a black jacket with yellow stripes on the arms from the shoulder down, blue jeans and black Nikes.
The attack happened just two blocks from President Barack Obama's home.
