SirenJack is a vulnerability that was found to affect radio-controlled emergency warning siren systems from ATI Systems. It allows a bad actor, with a $30 handheld radio and a laptop, to set off all sirens in a deployment.
By Balint Seeber
Full abstract: https://www.blackhat.com/us-18/briefings/schedule/#sirenjack-cracking-a-secure-emergency-warning-siren-system-11691