iOS 8.4.1 (build 12H5321) is an official Apple over-the-air update for the iPhone 4s, released on 2015-08-13T18:05:03Z. The update package is 1.09 GB. This is a delta (partial) update that requires 8.4.1 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 811881b14b0e940233c77e7fc5f9719c7944c132.zip.