-- Login information for as many as 225,000 Apple accounts may have been stolen using a sophisticated malware called KeyRaider that targets jailbroken devices -- those that have hardware restrictions removed and are no longer protected by Apple.
Cyber security company Palo Alto Networks, working alongside Chinese technology group WeipTech, published research detailing the breach, which apparently allows hackers to download apps using the person's account to remotely lock a device and hold it for ransom.
"We believe this to be the largest known Apple account theft caused by malware," researcher Claud Xiao wrote.
The malware appears to have been spread by being built into jailbreak tweaks, which are software additions not evaluated by Apple, Xiao said. The tweaks have been downloaded more than 20,000 times, leading researchers to believe at least that many people are taking advantage of the 225,000 stolen account credentials.
Some people have reported unusual purchasing history in their App Store accounts while others have had their devices locked for ransom, according to researchers.
Apple advises users to not jailbreak their devices due to security issues.
"Jailbreaking your device eliminates security layers designed to protect your personal information and your iOS device," Apple's support website explains. "With this security removed from your iOS device, hackers may steal your personal information, damage your device, attack your network, or introduce malware, spyware or viruses."
Palo Alto Networks said it provided the stolen account information to Apple on Aug. 26. It was also noted that researchers were only able to recover half of the stolen account information before the hacker fixed the vulnerability.