17 Pa.C.S. § 715

(a) General rule.--In any action brought to enforce a secondary right on the part of one or more members against any officer or director or former officer or director of a credit union because the corporation refuses to enforce rights which may properly be asserted by it, the plaintiff or plaintiffs must aver and it must be made to appear that the plaintiff or each plaintiff was a member of the corporation at the time of the transaction of which he complains or that his membership devolved upon him by operation of law from a person who was a member at that time.

(b) Security for costs.--In any such action instituted or maintained by a holder or holders of less than 5% of the outstanding share accounts of the credit union, the credit union in whose right the action is brought shall be entitled, at any stage of the proceedings, to require the plaintiff or plaintiffs to give security for the reasonable expenses, including attorney fees, which may be incurred by it in connection therewith and for which it may become liable pursuant to section 712(a) (relating to indemnification) (but only insofar as relates to mandatory indemnification in actions by or in the right of the corporation), to which security the corporation shall have recourse in such amount as the court having jurisdiction shall determine upon the termination of the action. The amount of the security may, from time to time, be increased or decreased in the discretion of the court having jurisdiction of the action upon showing that the security provided has or may become inadequate or excessive.