iOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone 8 (GSM), released on 2017-12-13T18:11:02Z. The update package is 585.3 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: 78efe4f78d4b62d5b557a0befc62f675886a9479.zip.