Disclosed herein is a processing device comprising a secured execution environment comprising means for bringing the processing device into a predetermined operational state; and a timer; a communication interface for data communication between the processing device and a remote device management system external to the processing device; wherein the secured execution environment is configured, responsive to an expiry of the timer, to bring the processing device into said predetermined operational state; and responsive to a receipt, from the remote device management system via said communications interface, of a predetermined signal, to restart the timer.