Twitter Users Can Now Use 2FA Without a Phone Number

Twitter this week announced that its users no longer need a phone number to add extra protection to their accounts via 2-Factor Authentication (2FA). 

Until now, the social platform required users to supply a phone number to receive login codes via text (SMS) messages, but additional options are now available, Twitter says. 

Twitter users currently have three different 2FA methods to choose from, namely text message, mobile security apps, and security keys. 

The use of security keys, however, still requires for either text message or authenticator app second factors to be enabled, given that the feature is only supported on the web. Support for security key-based 2FA has been available on Twitter for a year and a half. 

“Currently we require you to have a second method along with security keys since the latter isn’t currently supported outside web. If you’d like to disable SMS, you need to also have a mobile security app. We know this might not be ideal but we’re going to keep working on it,” Twitter security engineer Jared Miller explains. 

The company also updated its help article on how to use 2FA, to add the necessary information on how authentication apps could be used for this purpose. 

Twitter’s decision to expand the list of supported 2FA methods is more than welcomed, especially with the National Institute of Standards and Technology (NIST) denouncing SMS 2FA over three years ago. 

Earlier this year, the Twitter account of Jack Dorsey, the company’s CEO, was targeted by a SIM swapping attack, where hackers tricked the mobile phone operator into transferring Dorsey’s phone number to a SIM card they controlled. 

Although the hackers only used their access to post offensive tweets via SMS messages, SIM swapping is often used to bypass SMS-based 2FA, as login codes are sent to the attackers instead. 

Related: NIST Denounces SMS 2FA – What are the Alternatives?

Related: 6 Ways Attackers Are Still Bypassing SMS 2-Factor Authentication

Related: Ready or Not, Here Comes FIDO: How to Prepare for Success