iOS 11.4 (build 15F5079a) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2018-05-17T17:02:26Z. The update package is 41.13 MB. This is a delta (partial) update that requires 11.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 7b4f141d0ed3a7dd1c4365d7dd4f79fbbf61215f.zip.