Tracking Device
A technique that links your phone, TV, and computer into a single profile—often without your knowledge.
Cross-device tracking is technology that enables the tracking of users across multiple devices such as smartphones, television sets, smart TVs, and personal computers. It is a technique in which technology companies and advertisers deploy trackers, often in the form of unique identifiers, cookies, or ultrasonic signals, to generate a profile of users across multiple devices. This form of tracking is used primarily by technology companies and advertisers who use this information to piece together a cohesive profile of the user. These profiles inform and predict the type of advertisements the user receives.
- Type
- Surveillance Implant
- Origin
- Demon Technology
- Location
- Posterior Neck
- Function
- GPS-like Monitoring
- Removal Method
- Surgical Extraction
- Status
- Critical Plot Device
Lore & Background
Cross-device tracking initially emerged to associate a user's activity across multiple devices with a single profile. One historical method used website sign-ins to associate activity with an account, a form of deterministic cross-device tracking in which the user's devices are associated with their account credentials, such as their email or username. While the user is logged in, the company can access a history of websites visited and ads the user interacted with across computers and mobile devices. Cookies were later deployed by advertisers, providing each user with a unique identifier in the user's browser so that the user's preferences could be monitored. However, as users began using multiple devices—up to around five—advertisers had difficulty tracking, managing, and consolidating this data across multiple devices as the cookie-based model suggested that each device—whether a phone, computer, or tablet—was a different person. Other technologies such as supercookies, which stay on computers long after the user deletes his or her cookies, and web beacons, which are unique images from a URL, are also used by trackers and advertisers to gain increased insight into users' behavior. Browser fingerprinting can be used to identify users based on distinctive browser and device characteristics. Google's AdID can be used on smartphones in combination with cookies on a user's computer to track behavior across devices. One cross-device tracking method uses audio beacons, or inaudible sounds, emitted by one device and recognized through the microphone of another device, usually a smartphone. Cross-device tracking has also been discussed in relation to the Internet of things (IoT), in which devices such as office equipment, cars, and home appliances are connected through the internet.
In Their Own Story
In October 2015, the Center for Democracy and Technology submitted comments to the Federal Trade Commission (FTC) regarding cross-device tracking technology, specifically mentioning SilverPush. In March 2016, the FTC issued warning letters to 12 app developers using cross-device tracking 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. Studies have shown that 234 Android applications are eavesdropping on ultrasonic channels without the user's awareness. Applications such as SilverPush, Shopkick, and Lisnr are part of an 'ultrasonic side-channel' in which the app, often unbeknownst to the user, intercepts ultrasonic signals emitted from the user's environment, such as from a TV, to track which advertisements the user has heard and how long the person listened to them. SilverPush—the leading company using this technology—patented software enabling them to track TV ads based on audio stream above. Shopkick gives discounts to users who shop at stores which emit these ultrasonic beacons, allowing them to create a profile of the user. Lisnr uses a user's location data in tandem with ultrasonic beacons to give users coupons related to their activities. Another study suggested that Apple, Google, and Bluetooth Special Interest groups need to do more to prevent cross-device tracking.
Reader's Guide
Cross-device tracking can use audio beacons, or inaudible sounds, emitted by one device and recognized through the microphone of the other device. Audio 'beacons' can be embedded into television advertisements. In a similar manner to radio beacons, these can be picked up by mobile apps. This allows the behavior of users to be tracked, including which ads were seen by the user and how long they watched an ad before changing the channel. Humans interpret sound by picking up on different frequencies. Given the variety of sound waves that exist, humans can only hear frequencies that are within a certain range—generally from 20 Hz to 20 kHz. By the age of 30, most humans cannot hear sounds above 18 kHz. Ultrasound, which is shorter wavelengths greater than or equal to 20 kHz, enables the rapid transmission of data necessary for cross-device tracking to occur. Audio beacons are beacons that are embedded into ultrasound, so they cannot be heard by humans. These audio beacons are used to surreptitiously track a user's location and monitor online behavior by connecting with the microphone on another device without the user's awareness. Ultrasonic tracking technologies can pose massive threats to a user's privacy. There are four primary privacy concerns associated with this new form of tracking: media tracking, cross-device tracking, location tracking, and de-anonymization of users of Bitcoin and Tor.
Did You Know?
- Cross-device tracking can use ultrasonic audio beacons that are inaudible to humans—by age 30, most people cannot hear sounds above 18 kHz, while ultrasound starts at 20 kHz.
- In March 2016, the FTC issued warning letters to 12 app developers using cross-device tracking, warning they may violate the FTC Act if they claim not to track TV viewing habits while actually doing so.
- A study found that 234 Android applications were eavesdropping on ultrasonic channels without the user's awareness.
- SilverPush patented software enabling them to track TV ads based on audio stream above the range of human hearing.
- Ultrasonic tracking can de-anonymize users of Bitcoin and Tor by associating a mobile phone with those accounts via ultrasonic signals.