Researchers from Princeton University and University of Chicago have found that internet-connected TVs, which allow people to stream shows and movies on Netflix and Hulu, come with data trackers.

Trackers On Roku and Amazon Fire Channels

For the study, Arvind Narayanan, associate professor of computer science at Princeton, and colleagues built a bot that installed thousands of channels on Roku and Amazon Fire TVs and mimicked human behavior by browsing and watching videos.

The researchers found trackers on 69 percent of Roku channels and 89 percent of Amazon Fire channels. Narayanan said that some of these are from well-known firms such as Google, but many others are from companies that most people have never heard of.

The researchers found Google's ad service DoubleClick on 97 percent of Roku channels.

More alarmingly, some of the data collected, such as the device serial number and Wi-Fi network, are unique and can be used to pinpoint an individual. The researchers said that these data provide a more complete picture of who the users are. They also said that some channels even send unencrypted email addresses and video titles to the trackers.

"If you use a device such as Roku and Amazon Fire TV, there are numerous companies that can build up a fairly comprehensive picture of what you're watching," Narayanan said, according to the Verge. "There's very little oversight or awareness of their practices, including where that data is being sold."

Ineffective Countermeasures To Stop Data Collection

Users can turn off targeted advertising, but this only stops a user's advertising ID from being tracked and not the other uniquely identifiable information.

"We also discover widespread practice of collecting and transmitting unique identifiers, such as device IDs, serial numbers, WiFi MAC addresses and SSIDs, at times over unencrypted connections," the researchers wrote in their study.

"The countermeasures available on these devices, such as limiting ad tracking options and adblocking, are practically ineffective."