Executive Order on Imposing Certain Sanctions in the Event of Foreign Interference in a United States Election
This is the provision that mandates a full report to be submitted 45 days after the election.
"Section 1. (a) Not later than 45 days after the conclusion of a United States election, the Director of National Intelligence, in consultation with the heads of any other appropriate executive departments and agencies (agencies), shall conduct an assessment of any information indicating that a foreign government, or any person acting as an agent of or on behalf of a foreign government, has acted with the intent or purpose of interfering in that election. The assessment shall identify, to the maximum extent ascertainable, the nature of any foreign interference and any methods employed to execute it, the persons involved, and the foreign government or governments that authorized, directed, sponsored, or supported it. The Director of National Intelligence shall deliver this assessment and appropriate supporting information to the President, the Secretary of State, the Secretary of the Treasury, the Secretary of Defense, the Attorney General, and the Secretary of Homeland Security."
https://www.whitehouse.gov/presidential-actions/executive-order-imposing-certain-sanctions-event-foreign-interference-united-states-election/