how to identify a client?

hi out there

 

We need to do 2 factor authentication on Excel clients which access data cubes in a BI enabled Sharepoint site.

 

But these clients doesnt accept session cookies or similar - nor a pop-window for a 2. factor auth prompt. But if I could identify the client and permit/intercept that session I could request a auth push for a auth-request to a DuoSecurity client or MS Azure MFA client on the users smartphone - and hereby get a input field for a auth response. But how could I identify this session ?

 

br /tiwang