C3D first request problem

[Manuel_]

Hi all,

We have an application that has a login button and when you press it you can login with a certificate. This is working perfectly fine.

We have put in front of the app a virtual server with ssl profiles configured with C3D (Client Certificate Constrained Delegation) and add the C3D’s CA into the trusted store of the app’s server.

When we try to login through the virtual server we can and the app work as expected, the generated certificate reaches the app, the user is logged in and we see posible threahts on ASM.

However the login process is not exactly as if we do it directly with the app.

The first time a user tries to log in the browser ask for the certificate, the user selects it and then an error shows up in the browser but quickly dissapears beacause the browser automatically refreshes itself.

If the same user closes the browser and then open it and try to log in this time there is no error shown as the process goes normally like when the users log in directly in the app without the virtual server in the middle.

Client SSL profile:

Server SSL profile:

We also have an iRule like this on the virtual server to only ask for the certificate on the login page, not anywhere else:

when CLIENTSSL_CLIENTCERT {
    HTTP::release
}

when HTTP_REQUEST {
    # Some tests to determine if IS_LOGIN_PAGE
    if { IS_LOGIN_PAGE }{
        HTTP::collect
        SSL::session invalidate
        SSL::authenticate always
        SSL::authenticate depth 9
        SSL::cert mode request
        SSL::renegotiate
    }
}

Any thoughs on what could be the cause?

Any help is appreciated!

[mihaic]

try to remove : 

  SSL::session invalidate

[Manuel_]

Thanks for the reply but unfortunatly same thing happens.

[mihaic]

probably you need to do more troubleshooting and see what that error says.

Here is a link that might help you:

https://support.f5.com/csp/article/K15475

[Manuel_]

Thanks for the link.

I have tried tcpdump between the browser and F5 simultaneosly with another tcpdump between the F5 and the final server and what happens is the first time F5 sends a TCP Certificate Request to the browser and the user selects the certificate to log in no certificate arrives to F5 but then the browser refreshes itself, and without the user doing nothing, the certificate that he had selected before arrives to F5 and then is logged in the app correctly.

[mihaic]

have you tried with other browsers? are all acting the same?

I don't know what browser you use. But try with others.

[Manuel_]

Yes, all browsers act the same. I have tried with edge, chrome and firefox.

[mihaic]

Have you tried : 

 SSL::cert mode required

[Manuel_]

Yep and the same thing happens.

I think I have the solution, gotta do some testing and if it all works I'll post it here.

Thanks a lot for your help.

[Manuel_ · Accepted solution]

With the iRule like this the error does not occur:

when CLIENTSSL_HANDSHAKE {
  if { [SSL::cert count] != 0 } {
    HTTP::release
  }
}

when HTTP_REQUEST {
    # Some tests to determine if IS_LOGIN_PAGE
    if { IS_LOGIN_PAGE }{
        HTTP::collect
        SSL::session invalidate
        SSL::authenticate always
        SSL::authenticate depth 9
        SSL::cert mode request
        SSL::renegotiate
    }
}

The only problem I've seen happens if the user cancels the select certificate dialog in the browser but that doesn't worry us a lot.

[mihaic]

thanks!

Good to know.