Any savvy iPhone or iPad user will tell you that popups requiring you to enter your Apple ID and password are a pretty common thing. It usually happens while you’re inside Apple’s stores, although they can appear unexpectedly.
As a rule of thumb, do not enter your Apple ID when these popups show up in third-party apps. Apparently, they may be used to steal your Apple ID password.
Apple has a firm grip on the App Store, meaning that malware apps are not likely to be approved. But developer Felix Krause discovered that an app only needs about 30 lines of code to include a fraudulent “Enter your Apple ID password” popup that can be used to steal user data.