The hack that resulted in leaked celebrity photos led Apple to implement a stricter security policy by delivering push notifications to users using the iCloud.
At the beginning of the month, if someone logged in to iClοud from a new device, they would not receive any notice.
However, with the new measures that have been implemented, at least at least at this time, the account owner will receive a notification if someone has access to the service from web browsers.
Apple's warning email is quite clear and states "the Apple ID was used to connect to iCloud via a web browser. ”
The e-mail took at least ten minutes to receive the alert, informing that Apple ID had been used to us. This time is too much for an attacker to make changes to our account.
You can try it for yourself, to see the "immediacy" of the warning from Apple. Of course, if some people actually do, they'll need to change their account password immediately.