iOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone 8 (Global), released on 2017-12-13T18:10:46Z. The update package is 393.49 MB. This is a delta (partial) update that requires 11.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: ad77ef5659f62a7b37fb8f57c1b844d43b2cd831.zip.