Apple updated iCloud to increase security. Now there’s a two-step verification process that involves using a trusted device and an extra security code. For instance, you can receive the code via SMS, or Find my iPhone for iOS.
When they get through the authentication process, they can access their iCloud. This is all Apple’s way of increasing security on iCloud. For instance, in the past, I’ve had times when I register a new device or sign up on one and Apple sends an email informing me that a new device was registered under my Apple ID. It’s just another way of making sure I know what’s going on with my Apple ID.
For now, the two-step verification has reached the US, UK, Ireland, Australia and New Zealand. Looks like security just keeps getting tougher and tougher. For everybody.