Upgrade to Pro — share decks privately, control downloads, hide ads and more …

2FA, U2F, OOB, and Other Terrifying Security Acronyms

46093583d8895095adb1b0071c505af2?s=47 Eric Mann
November 16, 2017

2FA, U2F, OOB, and Other Terrifying Security Acronyms

In 2016, NIST announced it was deprecating SMS-based 2FA (second-factor authentication) from its Digital Authentication Guidance. As the internet works to harden application and online security, what are the proper options available for truly secure authentication? What are those OOB (out-of-band) transactions anyway? Why is identity security so hard? Come learn about the tools that define the identity security landscape and how to easily integrate strong identity verification methods with your existing services. BYOA (bring your own acronyms).


Eric Mann

November 16, 2017


  1. 2FA, U2F, OOB, and Other Terrifying Security Acronyms php[world] 2017

  2. SMS 2FA Horror Story

  3. None
  4. SS7 • Signaling System 7 • Developed in 1975 to

    manage phone network switching • The framework has several vulnerabilities • Anyone can track user movements with 70% success • Calls and messages can be forwarded to third parties
  5. Why SMS 2FA is Insecure

  6. Why SMS 2FA is Insecure

  7. Why SMS 2FA is Insecure

  8. Why SMS 2FA is Insecure

  9. Why SMS 2FA is Insecure

  10. NIST Discourages SMS • In 2016, announced that SMS was

    “deprecated” as a second factor • Later clarified who the deprecation was for • As of the latest guidance, SMS is still allowed, just discouraged
  11. So What Now?

  12. OOB • OOB means “out of band” • Applies to

    more than just security • Imagine a speaker sending their presentation ahead of time • … or a courier delivering a package to an event venue for you • The point is to leverage multiple channels of communication • It’s hard to leverage exploits in multiple channels simultaneously
  13. OOB: HOTP • HMAC-base One-Time Password • Leverages a shared

    secret key • Uses a counter to guarantee every OTP is unique • Can use a hardware or a software token
  14. OOB: TOTP • Time-based One-Time Password • Fundamentally identical to

    HOTP • Uses a timestamp as a counter • Also available in hardware or software
  15. OOB: Magic Links • Send a one-time password token via

    email • Tied to a user, functions like a password • Can also use as a first factor • Only as secure as your user’s inbox
  16. U2F • Universal Second (2) Factor • Open standard from

    the FIDO Alliance • Fast Identity Online • Industry group established in 2013 • Built on top of HMAC and asymmetric keys • Supported by (almost) all major browsers
  17. Mobile Push: • APNS - Apple Push Notification Services •

    GCM - Google Cloud Messaging • SNS - Amazon Simple Notification Service • Submit a challenge to a mobile device to be signed and returned • Can leverage a securely-stored private key APNS, GCM, SNS
  18. Other Providers • Auth0 - Magic links, SMS • Authy

    - App • Duo - App, 2FA • Yuibco - Hardware tokens
  19. Keep in mind … • NIST’s SMS deprecation is a

    recommendation, not a requirement • Using SMS for 2FA is better than nothing • SS7 is exploitable, but the exploits are difficult • All of these 2FA providers offer SDKs - use them • Never roll your own when it comes to auth - use a proven solution
  20. info@tozny.com (844) 628-2872 www.tozny.com THANK YOU!

  21. Questions?