iOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone 8 (Global), released on 2017-12-13T18:10:41Z. The update package is 585.28 MB. This is a delta (partial) update that requires 11.0.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: d0465c1392a032b397db85bfa49051a850bfe301.zip.