More Things about Federated Provisioning
By Nishant Kaushik on Feb 18, 2009
My previous post on federated provisioning generated some interesting responses, both in the comments and in the blogosphere (see responses from Ian, Pamela and Pat Patterson). The topic has been so engaging (starting with Jackson Shaw's post) that while I was writing this post I saw that Dave Kearns has made it the topic for a series in his newsletter.
Pat's post is definitely worth a read as it describes how Liberty Alliance has proposed a solution to the thorny issue of data exchange between the two parties in the case of Scenario 2: Just-In-Time Provisioning. It sounds like an elegant solution, especially since it solves the issue Karl brings up in the comments to my post regarding not overloading the SAML assertion with extraneous information. Would love to hear if anyone knows of any issues in the solution.
Ian and Pamela also discuss the issue of federated de-provisioning, which has also been a thorny issue in federation discussions. Pam talks about being able to initiate de-provisioning when a user who should no longer have access tries to authenticate. That is certainly one way to do it. But more often than not, de-provisioning cannot be initiated during an authentication flow because the reason the user should no longer have access is that they are no longer employed at the company they got federated from. Meaning: they cannot authenticate from the RP in the first place.
What harm then, is there in a federated account sitting around if it cannot be authenticated to? Well, the answer I usually get (from customers) is that in the reality of today's systems, creating federated access to a service often involves creating some sort of account in an underlying legacy system. An account that can be authenticated to outside of the federation context, albeit only from a back-channel. While this is a scenario less likely to get abused, it is nonetheless a scenario that security audits frown upon, and that get flagged for remediation as a compliance risk.
So what to do? Ian talks about expiring accounts that have not been accessed in a while. Out-of-band de-provisioning between the RP and the SP is also a possible option, as described by Pam. That makes the overall integration between Acme and Omega a blend of Scenario 1 and 2, where federated provisioning happens just-in-time, but de-provisioning happens out-of-band (probably on a periodic basis) through a well-defined interaction. The de-provisioning can be made real-time as well, in that the provisioning server at Acme can issue a de-provisioning SPML request to the provisioning server at Omega, just like it would to any internal system, when the user is de-provisioned at Acme.
As you can see, solutions abound, and customers can choose the one that suits their needs the best. So it is pretty obvious that it is possible to solve the federated provisioning/de-provisioning problem. The issue is that none of this is standardized or formally productized in any way, and is left as an exercise for the customer to solve (Translation: Costly integration problems when different vendor products are involved). And where this issue was a costly annoyance in federation deployments between businesses, SaaS (where this whole discussion started) takes this to a whole new level, creating a barrier for adoption.
But as Pat says "Seems like that might change now..."