Describe attack:
SS7, short for Signaling System 7, is a protocol telecom companies use to communicate with each other. As an internetworking protocol between big companies, it contains a high degree of trust. That is, if you're allowed to speak SS7 to a server at all, you're allowed to say almost anything you want with it. When people speak of "SS7 attacks", they usually mean telling another telecom to route a number to you. You can use this to bypass SMS MFA - if I can tell Google's upstream phone provider that I own your phone number, then when I try to log in to your Google account, I'll get the code texted to me, not you.
SS7, short for Signaling System 7, is a protocol telecom companies use to communicate with each other. As an internetworking protocol between big companies, it contains a high degree of trust. That is, if you're allowed to speak SS7 to a server at all, you're allowed to say almost anything you want with it. When people speak of "SS7 attacks", they usually mean telling another telecom to route a number to you. You can use this to bypass SMS MFA - if I can tell Google's upstream phone provider that I own your phone number, then when I try to log in to your Google account, I'll get the code texted to me, not you.