Re: [OAUTH-WG] Rotating client secret

[Warren Parad <[e-mail]>]

Why is #3 a problem, and why do the admin A incorrectly use App A to store
the service credentials of App B in their repository? Admin A should be
using their source control/database to store the tenant B client secret.


*Warren Parad*
Secure your user data and complete your authorization architecture.
Implement Authress <https://bit.ly/37SSO1p>.
<https://rhosys.ch>


On Mon, Jul 13, 2020 at 11:34 PM Amarendra Godbole <[e-mail]> wrote:

> Let me see if I can provide more details on the usecase:
> 1. A tenant is subscribed to SaaS application A and SaaS application B,
> and both applications are separately managed by different teams in the same
> organization. No assumption can be made about the trust between those teams.
> 2. Application A backend is supposed to access Application B. App B also
> has the authorization server. Both applications expose administration UI
> for its tenants.
> 3. App B admin generates client_id and client_secret, and hands them over
> to App A admin.
> 4. App A admin enters the client_id and clilent_secret in the UI, so the
> backend App A can now communicate with/access App B.
>
> #3 exposes client credentials of App B to admins of app A — *this is our
> problem*. As stated in #1, we cannot make any assumptions about the level
> of trust between the two groups.
>
> If OAuth2 provided a client credential rotation, this exposure of
> credentials can be limited to a small time window. The original
> client_secret can be a one-time-use-bootstrap, that App A backend exchanges
> for another secret from the authorization server. Generalizing it, the
> OAuth2 spec can provide for servers to trigger a client_secret rotation.
>
> To your analogy, the front-end app can “leak” the credentials during
> provisioning (it can be a simple copy/paste that the user has to do), thus
> creating a security issue. But if the credentials are one-time-bootstrap,
> then first time the front-end app connects to Google drive, drive changes
> the client_secret for a different one, which then would be used by
> front-end app in the future. Drive also has the ability to periodically
> rotate the client_secret in a similar manner. This assumes front-end app
> cannot access the client_secret once it is provisioned.
>
> Is this better? Thanks!
>
> -Amarendra
>
> --
> sent via recycled electrons, from my portable command center.
>
>
>
> On Jul 13, 2020, at 1:48 PM, Warren Parad <[e-mail]> wrote:
>
> I'm not sure if it is just me, but I'm not sure I'm totally following.
>
> I can see a concrete analogy being that, Tenant application B could be
> Google Drive, and Tenant application A being any front end app that wants
> to offer a service that saves files in a user's Google Drive. If
> application A wants to interact with application B offline then tenant A
> needs a service client/secret along with an authorization grant initiated
> through application A (currently via UI in OAuth2).
>
> Whether application A cycles the client secret or not seems like a
> different problem. But I think I'm missing something. Given the example I
> provided, would you be able to provide more insight into the problem you
> are seeing?
>
>
> *Warren Parad*
> Secure your user data and complete your authorization architecture.
> Implement Authress <https://bit.ly/37SSO1p>.
> <https://rhosys.ch/>
>
>
> On Mon, Jul 13, 2020 at 10:36 PM Amarendra Godbole <ag=
> [e-mail]> wrote:
>
>> Hi All,
>>
>> First post to the list, and hopefully I am articulate enough to describe
>> the problem I am facing — did OAuth ever consider an ability to dynamically
>> rotate client secret (part of the “client credentials” authorization
>> grant)? I stumbled across rfc7591 (OAuth 2.0 Dynamic Client Registration
>> Protocol), but the OAuth 2.0 implementation I am looking at [1], does not
>> support it. I also found some previous reference to client secret rotation
>> [2], but it does not discuss my use case.
>>
>> We operate a SaaS application A, which is supposed to talk with another
>> SaaS application B. Our customers subscribe to both, our application A as
>> well as application B. However, the teams adminstering A and B are separate
>> teams within the same organization, though we cannot assume the level of
>> trust between them. Let’s call them Tenant Admin A and Tenant Admin B. In
>> our usecase, application A is the client for application B, and application
>> B provides OAuth 2.0 authorization workflows. Now, Tenant Admin A has to
>> provision the "client credentials” authorization grant — in order to do
>> that, Tenant Admin B generates the client_id and client_secret, and sends
>> them to Tenant Admin B. There is the problem — as I earlier stated, we
>> cannot assume the level of trust between Tenant Admin A and Tenant Admin B,
>> and exchanging client_id and client_secret now means the circle of trust
>> for application B includes individuals who may or may not be trusted.
>>
>> One thought that occured to me was a provision in OAuth 2.0’s client
>> credentials grant flow was the ability to “bootstrap” a client application
>> — basically the client_secret is one-time-use-and-timebound-only, and
>> allows the client to exchange it for a different client_secret. In our
>> case, this can be handled by the SaaS application backend, thus making sure
>> the Tenant Admin A no longer have access to it once they provision the
>> client. This can be generalized, such that the authZ server can
>> periodically trigger client_secret rotation, and won’t require manual
>> intervention [3]. As I stated earlier, rfc7591 talks about this, but but in
>> the context of dynamic registration.
>>
>> Having the client secret rotation a part of the protocol exchange
>> messages, maybe a bootstrap, would be the ideal solution for our usecase.
>>
>> Or the bigger question: Did I misinterpret it all? Looking for guidance
>> from this list.
>>
>> Thanks in advance.
>>
>> -Amarendra
>>
>> [1] Microsoft Azure
>> https://docs.microsoft.com/en-us/azure/active-directory/develop/v2-app-types
>> [2]
>> https://mailarchive.ietf.org/arch/msg/oauth/7ICMSRI2tjfXDD1Bk_G-qNpLy-0/
>> [3] Auth0 rotate client secret:
>> https://auth0.com/docs/dashboard/guides/applications/rotate-client-secret
>>
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