Phone Numbers Were Never Meant as ID

One key lesson from the recent T-Mobile and several other breaches: our phone numbers, that serve as a means to identity and verify ourselves, are increasingly getting targeted, and the companies are neither showing an appetite to work on an alternative identity management system, nor are they introducing more safeguards to how phone numbers are handled and exchanged. From a report:
Identity management experts have warned for years about over-reliance on phone numbers. But the United States doesn’t offer any type of universal ID, which means private institutions and even the federal government itself have had to improvise. As cell phones proliferated, and phone numbers became more reliably attached to individuals long term, it was an obvious choice to start collecting those numbers even more consistently as a type of ID. But over time, SMS messages, biometric scanners, encrypted apps, and other special functions of smartphones have evolved into forms of authentication as well.

“The bottom line is society needs identifiers,” says Jeremy Grant, coordinator of the Better Identity Coalition, an industry collaboration that includes Visa, Bank of America, Aetna, and Symantec. “We just have to make sure that knowledge of an identifier can’t be used to somehow take over the authenticator. And a phone number is only an identifier; in most cases, it’s public.” Think of your usernames and passwords. The former are generally public knowledge; it’s how people know who you are. But you keep the latter guarded, because it’s how you prove who you are.

The use of phone numbers as both lock and key has led to the rise, in recent years, of so-called SIM swapping attacks, in which an attacker steals your phone number. When you add two-factor authentication to an account and receive your codes through SMS texts, they go to the attacker instead, along with any calls and texts intended for the victim. Sometimes attackers even use inside sources at carriers who will transfer numbers for them.