Monday, March 23, 2015

ASP.NET MVC Identity–Registration

I was listening today to DotNetRocks episode 1109 with Troy Hunt, a well known security expert. In this episode Troy was sharing the following story(I summarized it):

“Some people claim that they have hacked DropBox or iCloud. But instead the only thing they did was trying out a list of available usernames and password(acquired from other hacks), until one of them works.

To make this more difficult for a hacker, it’s important that your application doesn’t expose any information if a specific email address is used inside your application or not. For example, on the login page when a user types a wrong email address to login, don’t say that the email address can not be found but give a more generic error mentioning that ‘username and/or password are incorrect’. Do the same thing on your forgot password page, don’t tell the users that the email address  can not be found but tell them that ‘a password reset mail is send to the specified email address’. Last place where you could accidently expose if an email address is used or not is on the registration page. Allow users to use any email address they want and don’t tell them if the email address is already in use or not.

You maybe lose some usability, but you gain a lot in terms of security”.

His explanation made me wonder if  the built-in authentication system in ASP.NET MVC is following all these recommendations.

  • Let’s first try to register a user with an email address that is already used:


That’s bad, on the registration page, you get a specific error if the email address is already in use. -1 for ASP.NET MVC… Bedroefde emoticon

  • Let’s now try to log in using a non existing email address:


Same error message for an existing and non-existing user. +1 for ASP.NET MVC… Glimlach

  • Let’s now try to reset our password:



Same message no matter if the email address exists in the application or not. +1 for ASP.NET MVC… Glimlach


2 out of 3 doesn’t sound bad, but one location where information about your users is exposed is one location too much…

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