Microsoft Is Wrong About SMS-Based Two-factor Authentication

  • By Scott Goldman
  • Jan 04, 2021

Microsoft wants everyone to stop using SMS-based authentication. Their cybersecurity heart is in the right place but their logic is wrong. SMS-based two-factor authentication (2FA) is convenient, fast, doesn't require any additional apps and has a very low learning curve. They are correct in saying that it is flawed, but not for the reasons they think.

Microsoft's (and everyone else's) fundamental flaw in the argument against using SMS as the two-factor authentication method is that they are only considering SMS messages sent TO the phone. Those messages are inherently insecure for a variety of reasons. SMS messages by definition aren't secure because the codes are sent in clear text. Moreover, codes can appear on a phone's preview screen even when locked. In addition, having to enter a code on a web page introduces the potential for man in the middle (MITM) attack in addition to the hijacking of the inbound SMS.

However, like most other critics of SMS-based authentication they're missing a fundamental side of the equation: Phones work in both directions. Sending a code in a text FROM a phone is vastly more secure than sending one TO a phone. SMS authentication messages sent from phones are less vulnerable to hacking for a variety of reasons - but mostly for one big one that carriers implemented long ago.

Every phone has a unique "fingerprint" comprised of a combination of its IMEI (a kind of serial number for mobile devices) and the phone number assigned to it. Messages sent to carrier-sanctioned “short codes” cannot be spoofed to appear as though they come from another number. Why? Carriers prevented that long ago in order to stop two phones from using the same number, which would cost them money. The IMEI/phone number (the "fingerprint") matching process stops messages sent from a phone attempting to spoof a phone number because the number won't match the IMEI in the carrier's registration records. The result is that a mobile-originated 2FA message would never even reach the authentication server, thus eliminating any possibility of a false authentication.

The phone's "fingerprint" virtually eliminates any hacking when sending an authentication message via SMS. Add to this two additional factors and it becomes clear that this method is significantly superior to the current SMS 2FA method: First, man-in-the-middle attacks are completely eliminated (there's no web page into which a code must be entered). Second, sending an authentication text from a stolen phone is almost impossible because the phone has to be unlocked in order to send a text message.

The text-TO-phone SMS 2FA method is flawed in many ways but text-FROM-phone is not. Let's not throw the SMS-2FA-baby out with the authentication bath water.

About the Author

Scott Goldman is the CEO of TextPower, Inc.

Featured

  • From Surveillance to Intelligence

    Years ago, it would have been significantly more expensive to run an analytic like that — requiring a custom-built solution with burdensome infrastructure demands — but modern edge devices have made it accessible to everyone. It also saves time, which is a critical factor if a missing child is involved. Video compression technology has played a critical role as well. Over the years, significant advancements have been made in video coding standards — including H.263, MPEG formats, and H.264—alongside compression optimization technologies developed by IP video manufacturers to improve efficiency without sacrificing quality. The open-source AV1 codec developed by the Alliance for Open Media—a consortium including Google, Netflix, Microsoft, Amazon and others — is already the preferred decoder for cloud-based applications, and is quickly becoming the standard for video compression of all types. Read Now

  • Cost: Reactive vs. Proactive Security

    Security breaches often happen despite the availability of tools to prevent them. To combat this problem, the industry is shifting from reactive correction to proactive protection. This article will examine why so many security leaders have realized they must “lead before the breach” – not after. Read Now

  • Achieving Clear Audio

    In today’s ever-changing world of security and risk management, effective communication via an intercom and door entry communication system is a critical communication tool to keep a facility’s staff, visitors and vendors safe. Read Now

  • Beyond Apps: Access Control for Today’s Residents

    The modern resident lives in an app-saturated world. From banking to grocery delivery, fitness tracking to ridesharing, nearly every service demands another download. But when it comes to accessing the place you live, most people do not want to clutter their phone with yet another app, especially if its only purpose is to open a door. Read Now

  • Survey: 48 Percent of Worshippers Feel Less Safe Attending In-Person Services

    Almost half (48%) of those who attend religious services say they feel less safe attending in-person due to rising acts of violence at places of worship. In fact, 39% report these safety concerns have led them to change how often they attend in-person services, according to new research from Verkada conducted online by The Harris Poll among 1,123 U.S. adults who attend a religious service or event at least once a month. Read Now

Most   Popular

New Products

  • PE80 Series

    PE80 Series by SARGENT / ED4000/PED5000 Series by Corbin Russwin

    ASSA ABLOY, a global leader in access solutions, has announced the launch of two next generation exit devices from long-standing leaders in the premium exit device market: the PE80 Series by SARGENT and the PED4000/PED5000 Series by Corbin Russwin. These new exit devices boast industry-first features that are specifically designed to provide enhanced safety, security and convenience, setting new standards for exit solutions. The SARGENT PE80 and Corbin Russwin PED4000/PED5000 Series exit devices are engineered to meet the ever-evolving needs of modern buildings. Featuring the high strength, security and durability that ASSA ABLOY is known for, the new exit devices deliver several innovative, industry-first features in addition to elegant design finishes for every opening.

  • 4K Video Decoder

    3xLOGIC’s VH-DECODER-4K is perfect for use in organizations of all sizes in diverse vertical sectors such as retail, leisure and hospitality, education and commercial premises.

  • A8V MIND

    A8V MIND

    Hexagon’s Geosystems presents a portable version of its Accur8vision detection system. A rugged all-in-one solution, the A8V MIND (Mobile Intrusion Detection) is designed to provide flexible protection of critical outdoor infrastructure and objects. Hexagon’s Accur8vision is a volumetric detection system that employs LiDAR technology to safeguard entire areas. Whenever it detects movement in a specified zone, it automatically differentiates a threat from a nonthreat, and immediately notifies security staff if necessary. Person detection is carried out within a radius of 80 meters from this device. Connected remotely via a portable computer device, it enables remote surveillance and does not depend on security staff patrolling the area.