I am unsure about a "necessary software update" message.

[AC Question]

A popup saying I need to install a software update appeared on my Samsug S3 mini phone today and won't go away. It does not look legit and I can't tell where it came from. Is it malware?The notice gives two options: install now and install later. It is getting irritating in frequency of appearance.

 

[Tim1954]

Ignore all popups, go to settings... About device... Sofware updates... Update manually- this will search for software updates for you. While there, turn off auto updates.
Never trust any popups.