This method in which an attempt to attack a security processor is detected by the security processor itself comprises: measurements (50) of several different events occurring independently of one another in the absence of attack attempts, :building (52) the value of at least one attack indicator as a function of at least one index of concomitance between at least two different events measured, the index of concomitance representing the temporal proximity between the two different events measured, and detecting (54) an attack attempt if the value of the attack indicator crosses a predetermined threshold.