The victim was walking south in the 8700-block of South Cottage Grove Avenue around 3:30 a.m. when she was grabbed from behind by a man she did not know, police said.
He allegedly pulled her into the lot of a vacant building and restrained her, before sexually assaulting her and stealing from her.
The suspect is described as an African American man with a light complexion. He is about 47 years old, is between 5 ft. 7 in. and 5 ft. 8 in. tall and has a heavy build, police said.
The suspect also has a tattoo with the word "LIFE" or "LIVE" on his chest. He was wearing a black and red jacket, blue jeans, blue underwear and black and red shoes, police said.
Anyone with information about the sex assault or the suspect should call Area South detectives at 312-747-8271 or submit an anonymous tip at www.cpdtip.com.