A number of undocumented features in iOS have been found to essentially create backdoors for siphoning large amounts of users' personal data from Apple devices.
Jonathan Zdziarski, a researcher who often trains federal and state law enforcement agencies in forensic techniques, revealed the existence of the mostly hidden features.
The data-stealing avenues have evolved over the last few years and may have been used by the U.S. National Security Agency to collect data on potential targets, Zdziarski said.
In 2013, German magazine Der Spiegel reported that the NSA had developed a "software implant" for the iPhone called DROPOUTJEEP. The app could be used to pull or push information and collect text messages, contacts lists, voicemail and geolocation data. The revelations were based on documents provided by ex-NSA contractor Edward Snowden.
Apple has denied working with the NSA on backdoors to its products. The company did not respond to a request for comment Monday.
"I am not suggesting some grand conspiracy; there are, however, some services running in iOS that shouldn't be there, that were intentionally added by Apple as part of the firmware, and that bypass backup encryption while copying more of your personal data than ever should come off the phone for the average consumer," Zdziarski said in a blog post.
One service that bypasses backup encryption is called mobile.file_relay, which can be accesses remotely or over a USB connection, Zdziarski said.
While once thought benign, the service has evolved in iOS 7, the latest version of the iPhone and iPad operating system, to expose lots of personal data.
Zdziarski described the service as "very intentionally placed and intended to dump data from the device by request."
The personal data retrievable through the service include the address book, photo album and voicemail and audio files, geolocation data, a list of email and social media accounts and caches of offline content.
A large amount of metadata is also accessible, such as timestamps, filenames, sizes and creation dates of all files, according to a slideshow that accompanied a talk Zdziarski gave to the HOPE X conference recently.
Another service called moible.house_arrest was originally used to allow iTunes to copy documents to and from third-party applications. It provides access to the device library, cookies, caches and preference folders that provide "highly sensitive account" information from social media, such as Facebook and Twitter.
Why the services were intentionally added to the firmware of Apple devices is not clear, Zdziarski said. However, the services do not represent a zero-day vulnerability and do not represent a "widespread security emergency."
"My paranoia level is tweaked, but not going crazy," he said. "My hope is that Apple will correct the problem."
Zdziarski's research paper has been posted on the Web.