[keycloak-user] OpenID Connect: Is storing access token in browser sercure?

[Sebastien Blanc]

I'm not sure to understand you usecase and anyway the access token lifespan
should always be really short (it's 1 minute by default in Keycloak) so I
don't really see the point of storing it in the local storage.

On Thu, Mar 21, 2019 at 8:42 PM Timurhan Sungur <timurhan.s at gmail.com>
wrote:

>  <
> https://security.stackexchange.com/questions/205837/openid-connect-is-storing-access-token-in-browser-sercure
> >
> Hi,
>
> I'm currently in the phase of integrating my web-site to OpenID Connect
> provided by KeyCloak. The web-site is not a single page application.
> However, different parts of the application are delivered by different web
> services.
> In each site delivered by these different web services, the user can call
> a standard REST API. This REST API can only be accessed with an access
> token received from KeyCloak. Thus, the user needs to log-in on the
> web-site using authorization code flow of OpenId Connect <
> https://openid.net/specs/openid-connect-core-1_0.html> offered by
> KeyCloak <https://www.keycloak.org/> and use the access token given by
> the token endpoint. This request with the access token can be either sent
> by browser or by one of the back-end services delivering the current
> web-site. Thus, we can either do a a client-side integration or server-side
> integration with the REST API.
>
> Unfortunately, the server-side integration is not that feasible due to the
> complex structure of back-end systems. I cannot even integrate most of web
> services with KeyCloak. Thus, I could store the access token in the browser
> in local storage <
> https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage> and
> access to the REST API directly from browser. However, I'm still unsure if
> storing the access token in browser will bring a security vulnerability.
>
> I could not see any official statement regarding this in the standards or
> in the KeyCloak documentation, so far. I have seen applications both
> storing it in the back-end and storing in the browser and I still can't
> tell the exact security benefit of using a session over an access token
> when we store it in the back-end. I do not intend to save refresh token in
> the browser and use only authorization code flow with the help of a
> back-end service.
>
> My questions:
>
> Is it a security vulnerability to store the access token in browser? E.g.,
> in local storage, in a cookie with HttpOnly, or both of them?
> Is there a way to mitigate the security threat and still store it in
> browser?
> Is there a best practice or guideline for storing the access tokens of
> OpenID Connect that you could refer to?
> What is the difference from the security perspective between storing the
> access token and session, if we can use the session to access the API over
> an intermediary service?
> Thank you for your assistance in advance!
>
>
> Regards,
>
> Timur
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