Kentor.AuthServices 0.21.2 Security Release

Kentor.AuthServices 0.21.2 has just been released to NuGet. It is a security release fixing three issues.

  1. XML External Entity Injection (affecting .NET 4.5 only)
  2. Malicious IdP can cause write to arbitrary file
  3. Flawed ReturnUrl validation leads to Open Redirect

The first two issues were reported by John Heasman, Morgan Roman and Joshua Estalilla from DocuSign. While I have dreaded the day when I would get a security issue I am extremely happy with the professionalism of the disclosure. I got the report privately, including detailed descriptions, reproduction steps and solid recommendations on how to fix it. I am very grateful you took the time to review AuthServices and find the issues and for the detailed reports.

More details on the vulernabilities will be published later.

Kentor.AuthServices v0.20.0 Released

Half a years worth of pull requests with great features have finally been baked into an official release of Kentor.AuthServices which is now available on Nuget. The most important fixes are improved active/passive handling for the Owin middleware and full support for SHA256/384/512 as it is time to leave SHA1.

First of all I would like thank all contributors and users that have had to wait for this while I’ve been on parental leave. A special thanks to Explunit who has made a lot of valuable contributions as well as reviewing pull requests and taken part in design discussions.

Breaking Changes

The public API of AuthServices is getting more and more stable, but nevertheless there are some breaking changes.

  • The Owin Middleware is now once again Passive by default
  • The Owin Middleware will act as Active during Logout, even if it is configured as passive. This can be disabled with the StrictOwinAuthenticationMode compatibility setting.
  • On .NET 4.6.2 and later AuthServices now by default generates SHA256-based signatures and only accepts SHA256 or stronger signatures.
  • The “clever” ReturnUrl expansion has been removed as it proved to create more problems than it solved.
  • ReturnUrl open redirect issue fixed.

Kentor.AuthServices 0.18.1 Breaking Changes

Today we released Kentor.AuthServices 0.18.1. It contains a number of bug fixes, but also a couple of breaking changes to a mostly internal API and logout handling.

You are affected if…

  • you build a HttpRequestData yourself, instead of using a build in ToHttpRequestData() extension method.
  • you are using Single Logout and…
    • you have a ClaimsAuthenticationManager
    • you manually create a AuthServicesClaimTypes.LogoutNameIdentifier claim
    • you filter out claims that are persisted

Most users should not be affected, but if you match any of the above please read on.

TLS on Azure with Legacy Android

In a recent project using Azure, SSL worked perfectly on all devices – but those running Android 2.X. It turned out that legacy Android has limited support for modern SSL/TLS features such as SNI and subject alternative name.

2015-09-08 09_08_05-WebmailGetting TLS configuration right nowadays can be quite tricky. Google Chrome is aggressively pushing for deprecation of old insecure standards by showing warnings or even errors on sites using deprecated https settings. Using a certificate issued merely two years ago, with the standards where common then now shows an error because the SHA-1 algorithm is not considered to be safe for the two remaining years of the lifetime of the certificate. The Google Chrome team is definitely pushing hard for moving web cryptography to safer grounds.

On the other end of the scale (no, I won’t be complaining about Windows XP, it’s not that much of a problem any more) is another Google product: Android. Even with the blazingly fast technology development, people are (IMHO rightfully) expecting a multi €100-device to last for more than a few years. That means that a lot of devices out there are still running Android 2.X. In this particular project, the target audience are not that tech-savvy. A lot of the users even have had to invest in their first smart phone, making their call-and-sms-only phones to history. With that audience, we had to support those old devices. On the other hand SSL warnings or errors in Chrome was unacceptable, so we had to find something that worked for all those platforms – and we did. Oh and by the way, the budget was really, really tight, so we had to find something that wasn’t too expensive.

Secure Account Activation with ASP.NET Identity

Distribution of credentials to new users of a system is often done in an insecure way, with passwords being sent over unsecure e-mail. With ASP.NET Identity, the password recovery functionality can be used to create a secure account activation mechanism.

The scenario for ASP.NET Identity, in the default MVC template is to let users self register. Then there are mechanisms to confirm the e-mail address, to make sure that the user actually is in control of the given e-mail address. There are also support for letting the user associate the account with external sign on solutions such as Google, Facebook and Twitter. That’s perfectly fine, but not for most applications I build.

I’m building line of business applications. They are actually often exposed on the Internet as they need to be available for partners. But, they are not meant to be available through self registration for anyone on the Internet. Those applications are invite only. That means that a user account is created for a new user. Then that user somehow has to be notified that the account has been created. The usual way to do that is to create the account, set a good password like “ChangeMe123” and send the user a mail with the new credentials. There are two problems with this

  1. A lot of users don’t get the hint and keep the “ChangeMe123” password.
  2. The e-mail can be sitting unread for a long time in the inbox, until someone gets hold of it – and the account.

Fortunately, there is a much more secure way to do account activation with ASP.NET Identity without much coding at all – by reusing the password recovery mechanism.

Software Development is a Job – Coding is a Passion

I'm Anders Abel, a systems architect and developer working for Kentor in Stockholm, Sweden.

profile for Anders Abel at Stack Overflow, Q&A for professional and enthusiast programmers

Code for most posts is available on my GitHub account.

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