An Integrated Circuit (IC) includes functional circuitry and protection circuitry. The protection circuitry is configured to maintain a counter value, which is indicative of a cumulative amount of hostile attacking attempted on the functional circuitry over a lifetime of the IC, to detect events indicative of suspected hostile attacks on the functional circuitry, to decide, responsively to a detected event, on an update of the counter value depending on a time difference between the detected event and a most recent power-up in the IC, and update the counter value in accordance with the decided update, and to disable at least part of the IC in response to the counter value crossing a threshold.