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Software Updated Apr 11, 2024

Limefix SEP Utility: Downgrade iOS without blobs

Promotion image of Limefix SEP Utility article.

In 2020, the Pangu Jailbreak Team divulged insights from a security conference, shedding light on the Secure Enclave Processor (SEP) and a vulnerability they uncovered namely BlackBird. This vulnerability, when combined with checkm8 is an unpatchable SecureROM bug. It opens the possibility of loading custom SEP firmware and downgrading a device, all without the prerequisite of saved SHSH2 blobs.

Purchase Limefix SEP Utility

A demo version of Limefix was never released. This commercial software requires to be purchased before you can use it to downgrade your iPhone or iPad.

What is Limefix SEP Utility?

Limefix SEP Utility is an innovative tool designed specifically for A9 – A9X, harnessing the power of Blackbird to facilitate device downgrades without the reliance on SHSH blobs or the necessity for signed iOS firmware. With this cutting-edge software, you can effortlessly downgrade your iPhone 6S on iOS 15 to iOS 10 or iOS 9 and enjoy a seamless user experience.

Blackbird is a SEP exploit for A8-A10 devices. Similar to checkm8, it operates as a hardware exploit, and cannot be patched. This exploit empowers users to perform actions such as setting SEP NONCE, facilitating the restoration of SEPOS to an unsigned version. This capability overcomes a significant obstacle in the downgrading process. Essentially, it enables the seamless transition to any desired iOS version by initiating the booting of an older SEPOS.

Anticipate future releases of Limefix SEP Utility to extend its compatibility to A10 devices, broadening its utility across a wider range of iOS hardware. This premium software is available for purchase, with pricing options ranging from $12.99, offering users a flexible and affordable solution for their device downgrade needs. Tethered and unthreaded downgrades are possible.

Limefix Blackbird SEP Utility screenshot.

Downgrading iOS with blobs involved using saved SHSH blobs, which are digital signatures, to authenticate and install an older version of iOS onto your device. This process would not be possible if Apple was no longer signing the older iOS version. This method is no longer effective; nevertheless, the SEP Utility tool, leveraging the blackbird exploit, enables downgrades without the requirement for signed iOS firmware or the necessity of saving SHSH blobs for your device.

What's new

  • Fixed baseband.
  • Fixed activation.
  • All iServices work.
  • Siri works.
  • Optional removal.
  • Can now jailbreak externally.

SEP Utility supports tethered blackbird downgrades and untethered blackbird downgrades with SHSH blobs. You can also use the software to decrypt SEP KBAGs. SEP Utility will be released for macOS only. The release date has been officially announced as November 28, 2023.

Please note that devices other than A8-A10 will not receive support. Regrettably, this implies that iPhone 8, iPhone X, and all other A11 devices are not supported.

Supported devices

SoC Device
A9 iPhone 6S, iPhone 6S Plus, iPhone SE (1st gen), iPad (2017) 5th gen

What's new

  • The initial release of SEP Utility.

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