We present a novel attack named "Authenticator Rebinding Attack," which aims at the Fast IDentity Online (FIDO) Universal Authentication Framework (UAF) protocol implemented on mobile devices. The presented Authenticator Rebinding Attack rebinds the victim's identity to the attacker's authenticator rather than the victim's authenticator being verified by the service in the UAF protocol, allowing the attacker to bypass the UAF protocol local authentication mechanism by imitating the victim to

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... form sensitive operations such as transfer and payment. The lack of effective authentication between entities in the implementations of the UAF protocol used in the actual system causes the vulnerability to the Authenticator Rebinding Attack. In this paper, we implement this attack on the Android platform and evaluate its implementability, where results show that the proposed attack is implementable in the actual system and Android applications using the UAF protocol are prone to such attack. We also discuss the possible countermeasures against the threats posed by Authenticator Rebinding Attack for different stakeholders implementing UAF on the Android platform.