Debugging .NET HTTPS apps

We're currently going through a security audit at work hardening a third party application. One of the improvements is to switch from HTTP to HTTPS which makes verifying the rest of the changes is tricky.

The way I did it was to download/installed Fiddler (http://www.fiddlertool.com/) which is an inspecting proxy. I followed the instructions to enable https decryption, and told Windows to trust the fiddler root certificate (Moved from Personal->Certificates to Trusted Root Certificate Authorities->Certificates).

Checked IE worked and it was fine, then I modified the application.exe.config file under the Docs and Settings\user\Local Settings\Application Data\Vendor\App and added

<configuration>
  <system.net>
    <defaultProxy>
      <proxy proxyaddress="http://localhost:8888" />
    </defaultProxy>
  </system.net>
</configuration>

I thought I was being very clever, but it turns out I couldn't get it to work. So I switched to using HTTPS instead.

Fiddlertool is pretty cool though :)