Can Two-Factor Authentication actually fail?

You've probably read many times that two-factor authentication is a superb extra layer of protection against a thief hacking into your accounts, because gaining access requires entering a One Time Passcode (OTP)—sent via text or voice—into a login field. In other words, no phone, no access.

But CAN a hacker get the phone? Ask Deray McKesson, an activist with Black Lives Matter. Hackers got his phone.

Now, this doesn't mean they busted into his home while he was napping and took his phone. Rather, the thief took control of his mobile account.

The thief rerouted McKesson's text messages - to a different SIM card that the mobile carrier, Verizon, had issued to the thief. This is how the criminal got the two-factor code. Next thing, the imposter was in McKesson's Twitter and e-mail accounts.

So though two-factor is a pretty well-padded extra layer of protection, it can be circumvented.

"Someone called Verizon impersonating me," tweeted McKesson on June 10. The crook got a different SIM this way. The flaw isn't the two-factor system. In this case it was Verizon, allowing this to happen just too easily.

"Today I learned that it is rather easy for someone to call the provider & change your SIM," says a subsequent tweet. Though Verizon does require the last four digits of the user's SSN to get a new SIM card, this isn't enough to filter out imposters, as we see here. McKesson further tweeted he was "not sure" how the imposter knew those last four digits, but that "they knew it."

Verizon has since implemented additional safeguards.

So what really happened? How did someone get McKesson's SSN? Did he reveal it somewhere where he didn't have to? And then the wrong person saw it? Was he tricked into revealing it through a phishing e-mail?

Nevertheless, here's what to do:

• Set up a secondary code on your phone's account.
• This is a personal identification number that an imposter would have to reveal before any changes were made to the account—even if he gave out your entire SSN to the mobile company rep.