In the last two years, the marketing industry started to show a fast increasing interest in technologies for user cross-device tracking, proximity tracking, and their derivative monetization schemes. To meet these demands, a new ultrasound-based technology has recently emerged and is already utilized in a number of different real-world applications. Ultrasound tracking comes with a number of desirable features (e.g., easy to deploy, inaudible to humans), but alarmingly until now no comprehensive security analysis of the technology has been conducted. In this talk, we will publish the results of our security analysis of the ultrasound tracking ecosystem, and demonstrate the practical security and privacy risks that arise with its adoption. Subsequently, we will introduce some immediately deployable defense mechanisms for practitioners, researchers, and everyday users. Finally, we will initiate the discussion for the standardization of ultrasound beacons, and outline our proposed OS-level API that enables both secure and effortless deployment for ultrasound-enabled applications.