Porn sites are riddled with web trackers, including from Google, Facebook, and Oracle, according to researchers at Microsoft, Carnegie Mellon, and the University of Pennsylvania.

More than 22,484 porn sites were analyzed, of which 74% were found to contain Google trackers. Oracle had trackers on 24% and Facebook on 10%.

Google and Facebook said data from these trackers was not used to build marketing profiles of users.

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Facebook, Google, and Oracle are tracking the porn you watch, according to a new study first spotted by The New York Times.

Researchers from Microsoft, Carnegie Mellon, and the University of Pennsylvania analyzed 22,484 pornography sites using a tool called webXray to identify tracking tools feeding data back to third parties.

"Our results indicate tracking is endemic on pornography websites: 93% of pages leak user data to a third-party," the study concludes.

Of the sites scanned in March 2018, the study found Google or its subsidiaries had trackers on 74%, Oracle on 24%, and Facebook on 10%. That translates to roughly 16,638 sites with Google trackers, 5,396 with Oracle, and 2,248 for Facebook.

According to the paper, even enabling "incognito" mode on a browser was no defense, as even though such users' actions aren't stored in their history, the data still trickles out to these third parties.

The researchers warn that the highly sensitive nature of data leaking out of people's internet use is cause for concern. "The fact that the mechanism for adult site tracking is so similar to, say, online retail should be a huge red flag," one of the study's researchers, Elena Maris, told The New York Times. The study also found that only 17% of the porn sites were encrypted, leaving users vulnerable to hackers.

The pornography site Pornhub is one of the most visited websites in the US. Shutterstock

Trackers can be placed on sites for various reasons. Google Analytics, for example, feeds traffic data back to websites so they can monitor their traffic. Alternatively, Facebook offers sites the ability to embed its "like" feature, enabling sharing back to Facebook. In return, they receive data about the websites' visitors. Exactly what happens to the data, or which data specifically is being collected, is hard to scrutinize.

Read more: How hidden trackers on websites use "login with Facebook" to harvest your data

Facebook and Google said they did not use information collected from porn-site visits to build marketing profiles. A Google spokesman told Business Insider:

"We don't allow Google Ads on websites with adult content and we prohibit personalized advertising and advertising profiles based on a user's sexual interests or related activities online. Additionally, tags for our ad services are never allowed to transmit personally identifiable information to Google."

A Facebook spokesman echoed this in a statement to The Times. The person said the company barred sex websites from using Facebook's tracking tools for business purposes, such as advertising. The Times said Oracle did not respond to multiple requests for comment.

Facebook and Oracle did not immediately respond to requests for comment from Business Insider.