An inventive monitor monitors accesses to a resource in an electronic system, such that access to the resource is based on payments in electronic security value units. The monitor detects patterns of payments for the resource in electronic security value units, and compares the patterns of payments to predetermined patterns of payment. In addition, the monitor determines a difference in the compared patterns of payments to the predetermined patterns of payment, such that when the difference is greater than a predetermined threshold difference, an attack is indicated.