Data Privacy
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Data Security
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Fraud Management & Cybercrime
Web-to-App Pipeline Uses Meta Pixel and Yandex Metrica

American social media giant Meta and Russian counterpart Yandex each found methods to break through privacy protections enabled by Android users, say academics in newly disclosed research.
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The tracking systems use scripts embedded into mainstream websites for gathering visitor metrics: Meta Pixel and Yandex Metrica. The methods, which differ slightly in execution, take advantage of Android permissions to funnel cookies from websites that contain tracking scripts onto Meta or Yandex apps, where web activity data can be consolidated and shipped to remote servers.
Researchers primarily from a science institute in greater Madrid warned Monday that besides violating users’ privacy, web-to-app tracking opens the door to a malicious third-party app that could intercept the cookie funneling.
Roughly six million websites across the globe house Meta Pixel and close to 3 million websites contain Yandex Metrica, researcher say, citing figures from BuiltWith. Researchers said Meta apparently turned on its tracking system in September, while Yandex has been doing it since February 2017.
A Meta spokesperson in a prepared statement said it stopped the tracking “upon becoming aware of the concerns.” The spokesperson also said the social media giant is “in discussions with Google to address a potential miscommunication regarding the application of their policies.”
Using native Android apps to collect web browsing data defeats privacy protections such as user permission settings, browsing the web in incognito mode and resetting the device’s mobile advertising ID. Not even deleting cookies works against it. Researchers said they haven’t seen any other company besides Meta and Yandex do so.
Collected data is very detailed, Günes Acar, an assistant professor at Radboud University in the Netherlands, told Spanish newspaper El País. It includes whether users shop for a product online, whether they put product in a digital shopping cart, if the user completed the purchase or registered with the website. “There’s a ton of data. Basically, every time you do something, they send it to their server. It’s much more than simply knowing that you went to a webpage,” Acar said in a quote translated from Spanish.
Acar instigated the research at the Madrid science institute after spotting a website with Meta Pixel embedded using Android internals to transmit data. “I knew that the web page had various trackers, including Facebook’s. But all of a sudden I saw that there was a connection with the local host,” he told El País. A little digging by Acar found some app developers had spotted the feature in September but were at a loss to explain it. One wrote that the Facebook software development kit began including local host calls from Meta Pixel starting in October. “No acknowledgement has come from Meta at all on this though. My support request with them got a generic response and then ignored thereafter.”
One technique Meta used to bridge online code to their Android apps is known as “SDP munging.” The “SDP” stands for session description protocol, an internet standard for initiating streaming video or multimedia sessions. The method involves using JavaScript to modify SDP data by inserting – in Meta’s case – the _fbp
tracking cookie into a protocol message, which the Instagram or Facebook apps can see by monitoring for internet traffic on specific ports.
When Google earlier this year modified the mobile Chrome browser to stop allowing that type of SDP munging, Meta responded within days with a workaround, researchers said.
Google shipped countermeasures in May 26 update for the Android Chrome browser with protections under trial that would block Meta and Yandex from using known web-to-app techniques. Implementing a Google proposal for Local Network Access is likely what a long-term solution should look like, the researchers said.
Similar web-to-app techniques could theoretically work on iOS devices as well as smart TV platforms and desktops, researchers said – but that “no evidence of abuse has been observed in iOS browsers and apps that we tested.”