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Tanya Janca for Microsoft Azure

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Multi-Factor Authentication (MFA)

Multi-Factor Authentication (MFA)

This article is for beginners in security or other IT folk, not security experts. :-D 

Recently you may have noticed me calling out several Canadian banks for not allowing users to add multi-factor authentication (MFA) to their online banking accounts. This blog post will detail what I mean by this, why it's important, and why I'm pushing for it.

Update: you can follow community activities online on this topic with the hashtag #MFAally.

Me, hassling a Canadian Bank about their lack of MFA

Two-factor or multi-factor authentication (2FA or MFA) means using more than one factor to prove that you are the real, authentic, you. A "factor" of authentication is a method of proving who you are, to a computer. Currently there are only 3 types: something you have, something you are and something you know

"Something you have" can be your laptop, phone, a token that generates codes, your badge, and more.Something you are could be your finger print, an iris scan, your gait (the way you walk), or your DNA. Something that is physically unique to you.

"Something you have"

"Something you are" can be your fingerprint, an iris scan, the gait of your walk, your DNA, and more.

"Something you are"

"Something you know" could be a password, a passphrase, a pattern or a combination of several pieces of information (often referred to as "Security Questions") such as your mother's maiden name, your data of birth and your social insurance number. The idea is that it is only something that YOU would know.

**"Something you know"**

When we log into accounts online with only a username and password, we are only using one "factor" of authentication, and that is less secure than using 2 or more factors. Many times accounts that are broken into or data is stolen, it is often due to someone using only one factor. 
When passwords are breached, users that have a second factor of authentication are still protected. When someone tries to brute force a system or account that has MFA enabled, even if they eventually get the password, they won't have the second factor in order to get in. Using a second factor makes your online accounts significantly more difficult to break into.

Examples of MFA

Multi-Factor: Entering your username and password, then having to use a second device or physical token to receive a code to authenticate. The username and password are one factor (something you know) and using a second device is the second factor (something you have).

Not multi-factor: a username AND a password. This is two examples of the SAME factor; they are both something that you know. Multi-factor authentication means that you have more than one of the different types of factors of authentication, not one or more of the same type.

Not multi-factor: using a username and password, and then answering security questions. These are two of the same fact, something you know.

Microsoft Authenticator app
When Cloud Shell logged me out on stage (how embarrassing!) at #MSIgniteTheTour in Hong Kong this past winter, I used my username and password (2 things that I know, meaning two of the SAME factor), plus the Microsoft Authenticator app (something I had), on my phone (something else that I had), which asked for my finger print (something that I am). That means I logged back in using all three factors of authentication. Even though I know it inadvertently made a great demo of the Microsoft products I was using, getting logged out mid-demo was embarrassing... 
Demo-failure aside, let's talk about what MFA is, what it is not, and why it is so important.

Many in our industry are in disagreement as to whether or not using your phone to receive an SMS (text message) with a pin is a "good" implementation of MFA, as there are known security flaws within the SMS protocol and some implementations of it. My (potentially unpopular) opinion is that I would rather have a pretty-darn-good second factor of authentication rather than only one factor, and that if this is the trade off (convenience versus perfect security) to convince the average user to adopt 2FA, I'm in favour of using SMS as a second factor. 

The number one piece of security advice that Azure Security Center gives anyone and everyone is to enable multi-factor authentication on all of your subscriptions; protecting the keys to your (cloud) kingdom is paramount. In fact, enabling multi-factor auth (MFA or 2FA for short) is industry best practice, and is constantly prescribed by security professionals to technical and non-technical people alike for all of their important accounts. Yet strangely, less than 10% of accounts on Google and other popular platforms have 2FA enabled. Why?

I suspect that the reason is 2 fold; 1) it's not always convenient and 2) the public simply does not understand the risk. And while most of us are not in a position to change #1, every one of us can work on changing #2.

I'd like to appeal to you, dear reader, to try to explain MFA to someone in your life, at work or at home, and ask them to enable it on their important accounts. I'd also like to ask you to enable 2FA for yourself, both at home and at work, if you haven't already. It might save you or someone you love from some serious heartache.

Thank you for reading.

For this and more, check out my book, Alice and Bob Learn Application Security and my online training academy, We Hack Purple!

Top comments (3)

dwd profile image
Dave Cridland

I have never understood the argument that SMS-based 2FA is worse than no 2FA at all. TOTP isn't perfect either, and has different weaknesses (and is, in any case, not "real" 2FA since it's a shared secret). But I'll get what I can get.

radio_azureus profile image
Radio Azureus

THe only bad #MFA IMHO is a custom programmed system. 5 programmers can never see what hundreds can, so for example the system by steam is a bad one, since it only works with their app and uses just 4 tokens instead of 6. When you have accounts going in the 100+ that is just a hassle. WHen you lose access to the app, you are in lockout for days, before support can dislodge the account

andreasjakof profile image
Andreas Jakof

In Europe, due to the PSD2 Directive, it is mandatory from September on to support MFAfor money transfers.