Acting Detective Inspector Neil Forlong said the victim was understandably "shaken and distressed".
"We are supporting her, and have offered her the services of Victim Support.
"Officers are currently speaking to others who reside at the property and are also in the process of conducting an area canvas," he said.
He said a scene examination was underway and was expected to be completed today.
Mr Forlong said police were gathering details about the offender so they could release a description of the man as soon as possible.
He said it was important for people to keep their doors and windows locked.
"We have had some hot days lately and there is no sign of the temperature cooling down.
"If you are going to sleep with your windows open make sure you install some security stays."
Mr Forlong asked for anyone who may have seen a male acting suspiciously in the Linton street area between 1am and 3am this morning to contact police.
