The MacRumours website has a pertinent story warning of phishing attacks which perfectly emulate a request for your Apple password –
https://www.macrumors.com.
Some good advice in the article is as follows:
"As Krause says, users can protect themselves by being wary of these popup dialogues. If one pops up, press the Home button to close the app. If the popup goes away, it's tied to the app and is a phishing attack. If it remains, it's a system request from Apple.
Krause also recommends users dismiss popups and enter their credentials directly within the Settings app. "This was new to me.
Lorimer