This is a really awkward attack for a couple reasons. In general, a malicious extension may have no way to tell whether a request was blocked — the origin if the request doesn’t belong to the extension authors, and the portion of the extension outside the sandbox won’t be told which requests were allowed. And, if too many requests are blocked apparently at random, the user may well notice.
It’s surely possible to sneak out some data, slowly, over a noisy channel, but it doesn’t sound straightforward.
Compare to actual manifest V3, where exfiltrating the keys to the kingdom appears to be entire trivial as long as the extension doesn’t try to block ads.
This is a really awkward attack for a couple reasons. In general, a malicious extension may have no way to tell whether a request was blocked — the origin if the request doesn’t belong to the extension authors, and the portion of the extension outside the sandbox won’t be told which requests were allowed. And, if too many requests are blocked apparently at random, the user may well notice.
It’s surely possible to sneak out some data, slowly, over a noisy channel, but it doesn’t sound straightforward.
Compare to actual manifest V3, where exfiltrating the keys to the kingdom appears to be entire trivial as long as the extension doesn’t try to block ads.