I suspect that in your WhatsApp case, someone spoofed her phone number so that they received the verification SMS instead. SMS verification is recently considered an unsafe method, which is why there’s been a move towards two factor authentication apps.
I’m not confident though, which only proves your point! I’m a professional software developer who reads about things like this all the time and I only have guesses at what went wrong.
I suspect that in your WhatsApp case, someone spoofed her phone number so that they received the verification SMS instead. SMS verification is recently considered an unsafe method, which is why there’s been a move towards two factor authentication apps.
I’m not confident though, which only proves your point! I’m a professional software developer who reads about things like this all the time and I only have guesses at what went wrong.