Why didn't you do this as routine maintenance to prevent anything like this from happening to this severity? Sure you can't make it 100% immune from attacks, but you could make the data 98% safe.
It seems you don't have much experience building secure websites. What you do is building security in depth. You make sure nobody can get in, and you make sure there's nothing to see if somebody gets in. You always assume that someone _might_ figure out how to get around one defense, and have a second defense in place. That's what Apple did, and it worked. Most likely the attacker didn't get access to anything, and what there was to access was encrypted.
If you knew of ways to get past one of the defences, you would of course fix it. Somebody got in, which means they used a method that wasn't anticipated and couldn't have been fixed. Because of "security in depth", that breach didn't gain the attacker anything, but now Apple knows what they did and makes the necessary changes. It is quite possible that Apple's security developers have from time to time found possible attacks and quietly fixed them; you wouldn't notice it.
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Why didn't these hackers go after the NSA? They already have all Apple Dev Center data and lots more..
That's of course nonsense, and you know that. And if it was true, you wouldn't go after the NSA. You go after someone who can't lock you away for the rest of your sad life without a court case.
this shows that apple is no longer reliable and it may affect stocks greatly.
There goes the public trust...Apple....
Nonsense. There's security in depth in place. Someone got past one defense, was promptly detected, and other defenses stopped him. Exactly how it is supposed to work. Public trust is also based on how a company handles problems: Apple handled it by immediately shutting down the site, which is inconvenient, but the absolutely safe thing to do, and they promptly informed the affected people about what was going on. Others companies would have kept the site running, hoping that nothing else happens. That's the companies you can't trust.