I'm not an expert on this but hacking would probably be anytime someone uses someone else's credentials without that person's permission. In both of the articles I linked, the person pretended to be Apple Support to get passwords. In the celebrity case, he sent out emails from a fake Apple domain and in the second he pretended to be an Apple employee over the phone. I'm not sure what technically qualifies as what.
Let me encourage you to think about this a little more deeply.
Person A has an iCloud account that stores their photos. It is protected by their password.
Person B contacts Person A and pretends to be Person C—a person of authority. Through this social engineering, Person A gives Person B their login credentials.
Person B used those credentials to log into Person A's account and access their data. Person A did not have two factor authentication enabled, causing no challenge -> answer to be issued in response to the new login.
Make sense? This is how that celebrity "hack" worked.
Now: Explain to me how all this unfolded as a result of iCloud. Where was the weakness in iCloud's process or security?
Apple tells you to use a complex password. Apple tells you to not use that password anywhere else. Apple tells you never to give your password to anyone else, and says
specifically that no one at Apple will ever ask for your password. Apple tells you to enable two-factor authentication to prevent unexpected logins. Apple tells you to enable advanced data protection which encrypts
all data held by Apple, making it irretrievable by anyone without your password in the event of an actual data breach/MITM attack, not just a cheap social engineering stunt.
No one deserves to have sensitive or private photos stolen, not even a vapid celebrity. But good data security habits are an
individual responsibility.