You have a valid lease with the property owner. The owner remains the owner until the house is foreclosed upon. If the owner is abiding by the terms of the lease (providing you a place to live, with all the terms and conditions attached to it), then you are obligated to pay rent.
Foreclosure laws and tenancy rights vary from state to state. It is best to speak with an attorney before decidign to withhold rent. Keep copies of your rent checks handy; if your rental home is foreclosed upon, the new landlord may request proof of the payments made during the foreclosure process to (1) prove that you have paid your rent on time in accordance with your contract now assigned to the new landlord, and (2) to determine when payments to the new landlord will begin.
Bear in mind that anyone can purchase your rental home at auction. It may not necessarily be a bank.