A 25-year-old disability worker was walking along a track on Kirkham Drive in Greenvale about 7.45pm on October 13 when the assault occurred.
A man started to follow the woman as she walked past Kinloch Grove, heading towards Somerton Road, according to police.
They suspect the man may have loitered in the area for some time before grabbing the woman, who had headphones on, from behind.
He then allegedly sexually assaulted her and ran off along Kinloch Grove.
She sprinted after him but lost track of him on Castlehill Avenue.
The alleged offender is yet to be found.
He is described as being aged in his late teens to early twenties, with a tanned complexion.
He was wearing a black and green jacket, a black t-shirt, grey pants with a stripe and black shoes.
Police have released CCTV of a man who they believe may be able to assist with their enquiries.
The woman, who is too afraid to be identified, doorknocked homes in the area to get CCTV footage of the man to give to police.
She told 9News she was “very fearful” and “petrified” to leave her house.
“I used to go on a walk every day after work,” she said.
“I was just doing such a simple task.
“I just don’t want this to happen to anyone else.”