There is a sharp increase in the use of mobile devices to conduct account takeover fraud. Most end users dont know their credentials were stolen by malware and therefore cannot report the compromise. Mobile devices, and iPhones specifically, have an interesting trait: They all look the same. Not just physically, but also their device fingerprint. If a mobile-aware risk engine had visibility into the fact that the victims PC was infected with malware, and that shortly after, the credentials associated with that account were used from a mobile device, fraud would have been stopped.”]
Source: https://securityintelligence.com/mobile-account-takeover-when-device-id-isnt-enough/