The incident happened Nov. 21 when a woman was hiking on the trail along the 17000 block of Mulholland Drive, according to the Los Angeles Police Department.
Authorities say the suspect approached the woman from behind, forced her into a secluded area and sexually assaulted her.
The suspect is described as a 30-year-old man with a two-inch scar on his right forearm.
Anybody with information is urged to contact detectives at (818) 374-7717 or (877) 527-3247.
Authorities recommend hiking in pairs and carrying a cell phone in case of an emergency, as well as being aware of your surroundings.