Apple said it has completed more than 40 hours of investigation to date, and found that the iCloud accounts in question were compromised based on practices that are "all too common on the Internet."
The company's statement dispels rumors that a wider exploit of its iCloud services, including the Find My iPhone function, played a part in the leaks. Apple recommends that its users employ a strong password, and also enable two-step verification to maximize security.
The company first revealed on Monday that it was "actively investigating the incident, which saw private photos of numerous celebrities leaked onto the Internet. The original poster of the images on web forum 4chan indicated that the shots had been collected from Apple's online service, but also admitted to having gathered the photos from others, making it unlikely that they were actually privy to the technical details of the leaks.
The fact that many of the celebrities were shown taking "selfies" with Android or Blackberry handsets had cast even more doubt on iCloud's role. Other services, including Snapchat and Dropbox, have also been implicated at various times with similarly nonexistent levels of evidence.
Since the pictures first began to surface on Sunday, reports have emerged suggesting that the images have been circulating amongst a close-knit group of hackers and others for some time. According to Gawker, the collection of pictures are as a result of potentially years' worth of work by hackers.
The fact that all of the images leaked at once led many, including a number of mainstream media outlets, to assume that the result was a massive security breach, which many to draw the conclusion that Apple's iCloud was not secure. But the statement from the company on Tuesday makes it clear that Apple has found no such flaws in its systems, suggesting that the pictures may in fact have been part of a collection that grew over the years but stayed out of the public eye.
The iPhone maker's full statement is included below:
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.