Skip to main content

ASP.NET Core - Who stole my cookie?

I stumbled over a strange issue I had in ASP.NET Core. A cookie created in ASP.NET MVC didn’t show up in my requests in ASP.NET Core.

This cookie was used to share some user preferences between 2 subsites in the same domain. The original cookie was created without setting a SameSite value but was also not marked as secure or httponly.

I first updated the cookie generation logic to set both the Secure and HttpOnly value to true. This is not strictly required but as I’m only reading the cookie in the backend this is already a step in the right direction.

Let’s now focus on the SameSite value. SameSite is an IETF draft standard designed to provide some protection against cross-site request forgery (CSRF) attacks. Cookies without SameSite header are treated as SameSite=Lax by default. If you know that we need SameSite=None to allow this cookie for cross-site usage, that should certainly be our next step.

Remark: Cookies that assert SameSite=None must also be marked as Secure.

Although I could now finally see using the Web Developer tools that the cookie certainly is available as part of my request, it didn’t show up yet inside my ASP.NET Core application when checking the Cookies property on my Http request.

There was one other problem with my cookie and this was related to the data in the cookie.Let’s have a look:

Do you notice the ‘\’ in the value? This is causing the problem; the original code didn’t URL encode the cookie values. Although the old ASP.NET MVC application didn’t seem to bother, ASP.NET Core certainly does and didn’t want to load and parse my cookie.

I had to update the original code to start url encoding the value:

Labels:

Popular posts from this blog

Azure DevOps/ GitHub emoji

I’m really bad at remembering emoji’s. So here is cheat sheet with all emoji’s that can be used in tools that support the github emoji markdown markup: All credits go to rcaviers who created this list.
Read more

Podman– Command execution failed with exit code 125

After updating WSL on one of the developer machines, Podman failed to work. When we took a look through Podman Desktop, we noticed that Podman had stopped running and returned the following error message: Error: Command execution failed with exit code 125 Here are the steps we tried to fix the issue: We started by running podman info to get some extra details on what could be wrong: >podman info OS: windows/amd64 provider: wsl version: 5.3.1 Cannot connect to Podman. Please verify your connection to the Linux system using `podman system connection list`, or try `podman machine init` and `podman machine start` to manage a new Linux VM Error: unable to connect to Podman socket: failed to connect: dial tcp 127.0.0.1:2655: connectex: No connection could be made because the target machine actively refused it. That makes sense as the podman VM was not running. Let’s check the VM: >podman machine list NAME         ...
Read more

Cleaner switch expressions with pattern matching in C#

Ever find yourself mapping multiple string values to the same result? Being a C# developer for a long time, I sometimes forget that the C# has evolved so I still dare to chain case labels or reach for a dictionary. Of course with pattern matching this is no longer necessary. With pattern matching, you can express things inline, declaratively, and with zero repetition. A small example I was working on a small script that should invoke different actions depending on the environment. As our developers were using different variations for the same environment e.g.  "tst" alongside "test" , "prd" alongside "prod" .  We asked to streamline this a long time ago, but as these things happen, we still see variations in the wild. This brought me to the following code that is a perfect example for pattern matching: The or keyword here is a logical pattern combinator , not a boolean operator. It matches if either of the specified pattern...
Read more