Apple says its services including iCloud and Find My Phone were not breached in a leak of nude photos targeting Jennifer Lawrence, Kate Upton and other celebrities.
In a statement released Tuesday, Apple says certain celebrity accounts were compromised using "a very targeted attack" on user names, passwords and security questions.
"We are continuing to work with law enforcement to help identify the criminals involved," said Apple in a statement.
Apple's iCloud service was named as the entry point for hackers to access accounts of celebrities including Lawrence and leak their private photos. The FBI says they are investigating the leak.
In a blog post published Tuesday, Stefanie Smith of security firm Avast says its possible hackers could have obtained email addresses and passwords from events such as the breach on web marketplace eBay or through the Heartbleed exploit.
"If the celebrities whose photos have been exposed were affected by these breaches and used the same passwords on several accounts, including iCloud, it would have been easy for the hackers to steal their personal photos," says Smith.