No agreement which tends to diminish or defeat the interest of the corporation in any asset acquired by it under this chapter is valid against the corporation unless the agreement:
(1) Is in writing;
(2) Was executed by the eligible institution and any person claiming an adverse interest thereunder, including the obligor, contemporaneously with the acquisition of the asset by the eligible institution;
(3) Was approved by the board of directors of the eligible institution or its loan committee; which approval is reflected in the minutes of the board or committee; and
(4) Has been, continuously, from the time of its execution, an official record of the eligible institution.