How to understand what data a particular site reads when registering or logging in or any other interaction with it?

Question

Anonymity

There is a site on which there is a task to make multiregistration. When using antidetect browsers such as multilogin, linken sphere - registrations end with auto-blocking, when using antidetect virtualbox - 50/50. Tell me how to analyze what the site reads? With the help of what tools and based on this, to fine-tune existing products for multi-accounting?

Answer 1

When accessing a site, HTTP headers are sent to it, which contain some information. Next, data from the site is downloaded to the client, including scripts that are executed on the client. These scripts collect the rest (most) of the information about the client. The client is usually a browser, but it can also be another program pretending to be a browser.
You can only analyze sent headers and downloaded scripts. You need to know at least JavaScript to figure out exactly what information the scripts collect.
However, it will be more difficult to understand the auto-blocking logic, because all the logic happens on a server whose code you do not have access to. The logic can be complex, such as parsing system fonts and tracking site behavior, including mouse movements. But the logic can also be simple, like if the browser fingerprint matches for two clients, then they both get banned.