Web ad firms scrape email addresses before you press the submit button

Tracking, marketing, and analytics firms have been exfiltrating the email addresses of internet users from web forms prior to submission and without user consent, according to security researchers.

Some of these firms are said to have also inadvertently grabbed passwords from these forms.

In a research paper scheduled to appear at the Usenix ’22 security conference later this year, authors Asuman Senol (imec-COSIC, KU Leuven), Gunes Acar (Radboud University), Mathias Humbert (University of Lausanne) and Frederik Zuiderveen Borgesius, (Radboud University) describe how they measured data handling in web forms on the top 100,000 websites, as ranked by research site Tranco.

The boffins created their own software to measure email and password data gathering from web forms – structured web input boxes through which site visitors can enter data and submit it to a local or remote application.

Providing information through a web form by pressing the submit button generally indicates the user has consented to provide that information for a specific purpose. But web pages, because they run JavaScript code, can be programmed to respond to events prior to a user pressing a form’s submit button.

And many companies involved in data gathering and advertising appear to believe that they’re entitled to grab the information website visitors enter into forms with scripts before the submit button has been pressed.

[…]

“Furthermore, we find incidental password collection on 52 websites by third-party session replay scripts,” the researchers say.

Replay scripts are designed to record keystrokes, mouse movements, scrolling behavior, other forms of interaction, and webpage contents in order to send that data to marketing firms for analysis. In an adversarial context, they’d be called keyloggers or malware; but in the context of advertising, somehow it’s just session-replay scripts.

[…]

Source: Web ad firms scrape email addresses before you know it • The Register

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