How We Bypassed SIM Binding in a Real Payment App: Bugsmirror Red Teaming Case Study

SIM binding is widely used in mobile payment and fintech apps as a core security control to ensure that only the registered SIM and device can initiate transactions. However, real-world testing shows that this mechanism is often built on assumptions that no longer hold true in modern threat environments. This case study breaks down the SIM binding process, highlights where current implementations fall short, and explains how these gaps can lead to full account takeover. It also emphasizes the need for runtime protection and stronger validation mechanisms to defend against evolving mobile threats.