You can download the IPSW from ipsw.me (you actually grab the file straight from Apple and it's digitally signed, so the malware risk is zero) and perform the u

You can download the IPSW from ipsw.me (you actually grab the file straight from Apple and it's digitally signed, so the malware risk is zero) and perform the update yourself by option-clicking the Update button in the iPhone window in Finder.