The attack took place at around 1.30am on new year's day in the area known as the tunnel, near the Vault nightclub in Aviemore.
Police Scotland want to speak to people who may have been in the area at the time.
In a separate incident, police in Aviemore are also seeking witnesses to an alleged assault on a 34-year-old man at around 12.45pm on Monday, December 30.
The man was attacked while he was walking on the B9153 Carrbridge to Kinveachy Road. A number of passing motorists stopped to help and police are keen to speak to them.
The male victim was approximately 6ft, wearing dark waterproofs and carrying a large rucksack.