[keycloak-dev] Same Refresh token can be used multiple times to obtain access token

Mon Oct 12 20:26:01 EDT 2015

Hi Stian/Marek,  Thanks for your attention in the matter.Probably you are referring to one other issue in client level, but Mike & I are referring at User level within or across client.
User John Doe authenticates with his credentials and obtains token pair A1R1   
   - After A1 expires, app refreshes the token pair to A2R2 USING R1   

   - After A2 expires, app refreshes the token pair to A3R3 USING R1 (ideally it is should use R2 as it is the latest refresh token)   

In order to achieve this functionality, I was wondering why can't we use existing last refresh time from User session rather then checking it in the client session.IMHO, adding one more validation in the ValidateToken method in TokenManager class like this should resolve the problem.

        // after userSession is determined either for offline token or online token...
        if(oldToken.getIssuedAt() < userSession.getLastSessionRefresh()) {
            throw new OAuthErrorException(OAuthErrorException.INVALID_GRANT, "Stale refresh token - already used");
        }

Please let me know if you see any pitfalls other than the backward compatibility for existing keycloak users. I can work with you to merge this change & test it in the master.
BestKamal

      From: Stian Thorgersen <sthorger at redhat.com>
 To: Marek Posolda <mposolda at redhat.com> 
Cc: "Jagadevan, Kamal" <kamalakannan.jagadevan at hpe.com>; "keycloak-dev at lists.jboss.org" <keycloak-dev at lists.jboss.org> 
 Sent: Wednesday, October 7, 2015 8:38 AM
 Subject: Re: [keycloak-dev] Same Refresh token can be used multiple times to obtain access token

You're right, we'd have to introduce a lastRefresh on ClientSession

On 7 October 2015 at 14:35, Marek Posolda <mposolda at redhat.com> wrote:

  On 07/10/15 14:23, Stian Thorgersen wrote:

 We should make this configurable. For those worried about security they can enforce new refresh tokens as well as offline tokens will replace the old tokens. It would be fairly simply to implement. If enabled we would only allow refresh token where iat is >= the last session refresh time. 
 I was also thinking about this possibility. However if you have 2 clients and you refresh the token for client1, the refresh token of client2 won't be valid as his "iat" will be older. Also SSO login currently refreshes lastSessionRefresh on UserSession. However maybe we can introduce lastSessionRefresh to ClientSession as well?

 Marek

  I wouldn't make it default behavior for two reasons: 
  * It would break existing clients if they expect to continue using the old refresh token * It comes at a performance cost as clients will have to store the new refresh tokens and offline tokens each time they refresh the token * For offline tokens Keycloak would also have to persist the last refresh time each time the offline token is refreshed 
  I think we'd need to make it a realm wide configuration option.

 On 7 October 2015 at 14:12, Marek Posolda <mposolda at redhat.com> wrote:

  The points are valid and security can be always improved, however sometimes improving security makes things complicated with the not-so-big advantage... IMO admin should always protect the machine to make sure that nobody unauthorized has access to refresh tokens. And for the transport, HTTPS should be always used. But feel free to create JIRA and we will see...

 When user or client is deleted, all refresh/offline tokens will defacto become invalid as well and can't be used anymore. You're right that offline token is still valid after user logout. User can revoke it manually in account management or admin can revoke it in admin console. However refresh token is invalid after user logout. All refresh/offline tokens for  particular client can be revoked by admin by set notBefore policy to now, which can be done in admin console in "Revocation" tab of particular client.

 Marek  

 On 07/10/15 04:27, Raghuram Prabhala wrote:

  Very valid points Mike and even I have similar concerns. But please do understand that even if the refresh  token is stolen or compromised,it cannot be used by any client unless both the client_id and client_secret are also compromised/stolen. But nevertheless, it is a good practice to assume the worst  and add in protective measures to minimize the chances.  
  Marek/Bill/Stian - Even our organization is very particular that such potential security issues be addressed.  Can this be taken up? BTW I am not sure if you have an API/End point to invalidate tokens for those that are either compromised or must be invalidated as either the user or client is no longer  active. If you do not have one then it is a good idea to make one available. 
  Thanks, Raghu 
      From: "Kuznetsov, Mike" <mikhail.kuznetsov at hpe.com>
 To: "keycloak-dev at lists.jboss.org" <keycloak-dev at lists.jboss.org> 
 Cc: "Jagadevan, Kamal" <kamalakannan.jagadevan at hpe.com> 
 Sent: Tuesday, October 6, 2015 4:34 PM
 Subject: Re: [keycloak-dev] Same Refresh token can be used multiple times to obtain access token

    Hello,    The reason I brought this up is that we are currently  working on migrating out authentication from a commercially available  product called Ping to Keycloak. We noticed that Ping invalidates the refresh token after it is used once, while Keycloak does not.    I and my colleague, Kamal are concerned that by not  invalidating the refresh token after first use, we may be opening a security  hole. While SSL may protect the token in transit, we can see a scenario where the refresh token would be compromised or stolen from  the client itself. In this case, the stolen refresh token could be used to get new access tokens without the owner of the client  machine knowing.     However, if the behavior was changed so that the refresh token  could only be used once, then either: 1.       If the owner of the client machine would use the  refresh token first, then the stolen refresh token could not be used 2.       If the stolen refresh token would be used first, then  the client machine would not be able to use it and the user of that client machine  could be alerted that something was wrong. This user could then reset their password or invalidate all of their access and refresh  tokens.    Furthermore, we are concerned about this same scenario, but with the  offline token. My understanding is that the offline token does not  expire and that it can’t be invalidated by logging out  the user or changing the user’s password. Have you thought about this scenario?    Thank You, 
 Mikhail Kuznetsov Software Engineer Hewlett Packard Enterprise    

     From: Marek Posolda [mailto:mposolda at redhat.com] 
 Sent: Tuesday, October 06, 2015 1:16 PM
 To: Raghu Prabhala
 Cc: Kuznetsov, Mike; keycloak-dev at lists.jboss.org
 Subject: Re: [keycloak-dev] Same Refresh token can be  used multiple times to obtain access token       Hi Raghu,

 >From the specs, it looks to me that this is not anything mandatory.  The paragraph is starting "For example". Feel free to create JIRA, but I personally can't promise anything regarding this...

 Marek

 On 06/10/15 17:37, Raghu Prabhala wrote:  
  Hi Marek - section 10.4 of rfc6749 mentions that the prior refresh  token should be invalidated but retained by the server - to handle compromise of refresh tokens as they  are long lived.         Thanks,   Raghu

 Sent from my iPhone   
 On Oct 6, 2015, at 10:53 AM, Marek Posolda <mposolda at redhat.com> wrote:  
   You're right, same refresh token can be used more  times. However it is still better to use refresh token R2 in your step 3 instead of using old refresh  token R1 because R2 has updated timestamp (each token is valid just for 30 minutes or  so, depends on the configured SSO session idle  timeout).

 Or are you referring that this is  security issue and potential possibility to Man  in the middle? If you use HTTPS (which is recommended for production environment, and  especially if you have unsecured/untrusted  networkl), this shouldn't be an issue.

 Marek

 On 06/10/15 16:34, Kuznetsov, Mike  wrote:  
 Hello,   I noticed that with Keycloak, it seems that refresh  tokens are still valid after they are used once. This means that Keycloak does not invalidate Refresh Tokens after they  have been used once.   I am able to successfully execute the following flow: 1.       Obtain Access Token (A1) and Refresh Token  (R1) 2.       Use Refresh Token (R1) to obtain new Access  Token (A2) and Refresh Token (R2) 3.       Use same Refresh Token (R1) again to obtain  new Access Token (A3) and Refresh Token (R3)     Can you please tell me if this is the intended  functionality?   Thank You, 
 Mikhail Kuznetsov Software Engineer Hewlett Packard Enterprise   

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