Weak Passwords and Security Questions on iCloud accounts.
Apple confirmed that certain celebrity accounts were compromised that results in massive leak of private naked photos of high-profile celebrities.
After a 40-hour probe, California tech giant said that the attacks were on individual Apple accounts. However, they were not a result of a breaches of iCloud or Find my iPhone, as what was reported ealier.
According to Apple:
"We wanted to provide an update to our investigation into the theft of photos of certain celebrities. When we learned of the theft, we were outraged and immediately mobilized Apple's engineers to discover the source. Our customers' privacy and security are of utmost importance to us. After more than 40 hours of investigation, we have discovered that certain celebrity accounts were compromised by a very targeted attack on user names, passwords and security questions, a practice that has become all too common on the Internet. None of the cases we have investigated has resulted from any breach in any of Apple's systems including iCloud® or Find my iPhone. We are continuing to work with law enforcement to help identify the criminals involved.
To protect against this type of attack, we advise all users to always use a strong password and enable two-step verification. Both of these are addressed on our website at http://support.apple.com/kb/ht4232. "
Apple encourages its users to carefully password-protect their Apple accounts andto turn on Two-step Verification. Better safe than sorry.