OpenAI has integrated a cookie into ChatGPT that links user behavior on the internet with their account when visiting third-party websites.
A researcher known as Buchodi published a technical report analyzing the entire tracking chain of the chatbot’s advertising platform, codenamed bazaar.
According to him, the advertising code for sites functions as a tracking pixel. When ChatGPT is launched, the service creates an identifier, links it to the account, and records it in the __obi cookie for the .openai.com domain.
When a user visits a commercial website with OpenAI’s advertising pixels, the browser automatically transmits __obi in the request and sends it back to the server.
The researcher replicated the mechanism in the Chrome browser for Android and verified it using two independent methods. According to him, the domains bzr.openai.com and bzrcdn.openai.com are involved in the scheme.
During observations, he matched 936 pixels on 1029 hosts and counted 23,929 requests without a query string in the URL.
What is Transmitted?
The solution transmits conversion events, optionally encrypted email addresses, phone numbers, names, and geolocation down to the postal code, claims the cybersecurity expert. Hashing is performed using the SHA-256 algorithm in the browser.
The tool collects not only the information provided by the advertiser but also data from the page, forms, and tag management systems.
According to Buchodi’s calculations, general data collection occurred in 685 cases, while extended transmission occurred in 255 cases. Emails and phone numbers were sent in hashed form, while country, region, city, and postal code were sent in plain text.
The researcher claims that the mechanism could also affect some unauthorized users. Of the 932 decoded sync tokens, 736 were related to users with accounts, and 196 to anonymous users.
Buchodi emphasized that the observation is limited to Chrome for Android. Safari blocks third-party cookies, and all browsers on iOS use WebKit.
He compared the scheme to practices used by Meta and Google in the companies’ social networks.
“The mechanism is standard for advertising technologies. However, its use in AI-based chat products is unprecedented. People share things with them that they wouldn’t post on social media,” the researcher added.
In February, OpenAI launched ads in ChatGPT for adult users of the low-cost Go plan and those without a paid subscription.
