Doulci Team iPhone 4S downgrade
The iPhone 12 might feature a design inspired by the iPhone 4. Reuters

The Doulci Team, a group of Dutch iOS jailbreak developers, claims to be the first group to successfully downgrade an Apple Inc. (NASDAQ:AAPL) iPhone from iOS 7.1 to iOS 5.1.1.

The iOS developer group published a video on Thursday, purporting to show a successfully downgraded iPhone 4S running iOS 5.1.1. According to a blog post by the Doulci team, this was accomplished without the use of SHSH blobs, a small piece of data that Apple previously used to authenticate and authorize iOS software updates. Users of iOS devices and jailbreak software, which remove software limitations of iOS, previously were able to save that SHSH blob information to get around Apple's software update authentication servers.

The SHSH blobs were used fairly often by jailbreak users to upgrade or downgrade iOS at will, until Apple changed its software update authentication process with the release of iOS 6, rendering the SHSH data useless, according to iOS developer Jay Freeman.

The video posted by the Doulci Team clearly shows an iPhone 4S running iOS 5.1.1. But, the developer group has yet to release more details on how the iOS downgrade was accomplished. More details about the exploit used to accomplish this software downgrade are expected to be released soon, according to the Doulci Team.

The Doulci Team is responsible for a software tool released in May that reportedly is able to bypass the Apple iCloud Activation lock on iOS devices. The Dutch iOS developer group announced on Wednesday that it's also working on a jailbreak for iOS 7.1.1, which currently doesn't have publicly available jailbreak software.