app developers using SilverPush code in their apps. The FTC warned these developers that they may be violating the FTC Act if they state or imply that their apps are not tracking television viewing habits when they in fact are. Shortly after the FTC warning, SilverPush made an official statement that they are ending the Unique Audio Beacon service. However, as of 21 March 2016, SilverPush is still advertising Unique Audio Beacon on their website. In November 2016, researchers from UCL, UCSB and PoliMI demonstrated the security and privacy implications of the ultrasound cross-device tracking (uXDT) technology used by SilverPush. The most notable of their attacks uses uXDT-enabled applications to deanonymize Tor users. In May 2017 SilverPush technology was again the subject of research: "A team of researchers from the Brunswick Technical University in Germany discovered [234] Android apps that employ ultrasonic tracking beacons to track users and their nearby environment. Their research paper focused on the technology of ultrasound cross-device tracking (uXDT)." See also Air gap (networking) BadBIOS Near sound data transfer SlickLogin Cross-device tracking References External links CDT letter to FTC FTC warning letter SilverPush wiki SilverPushUnmasked on GitHub Demo:Tor deanonymization using uXDT Mobile applications Internet privacy