Methods, systems, and apparatus are presented for processing a remote lock command message. In one aspect, a method includes receiving, by a mobile device, a remote lock command message comprising a lock command and specifying a passcode to be set by the mobile device, locking the mobile device in response to the received remote lock command message, setting an unlock passcode associated with the mobile device to the specified passcode, and generating an acknowledgement message in response to the remote lock command message. Further, receiving the remote lock command message can include accessing a subscribed topic hosted on a notification service, the subscribed topic being associated with a lock command, and retrieving the remote lock command message from the subscribed topic. Additionally, locking the mobile device can include locking a display such that access to information stored on the mobile device and device functionality are blocked.