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

Kuznetsov, Mike mikhail.kuznetsov at hpe.com
Tue Oct 13 15:03:35 EDT 2015 

Hello,

As advised earlier, I have put a JIRA ticket for this issue: https://issues.jboss.org/browse/KEYCLOAK-1961

We are excited to start using Keycloak to support our product, but right now we are blocked due to this issue because it has been flagged by our security team when they were reviewing our design.

Over the past few days, we have tried to overcome this issue by trying to revoke either the specific access token / refresh token if it is used more than once, or trying to revoke all the tokens for the user. However, we were unable to find a mechanism that would let us do this. Do you know if there is any mechanism to revoke a specific token, or to revoke all tokens for a user? Are there any plans to implement this in the future?

Thank You,

Mikhail Kuznetsov
Software Engineer
Hewlett Packard Enterprise




From: keycloak-dev-bounces at lists.jboss.org [mailto:keycloak-dev-bounces at lists.jboss.org] On Behalf Of Kamal Jagadevan
Sent: Monday, October 12, 2015 8:26 PM
To: stian at redhat.com; Marek Posolda
Cc: keycloak-dev at lists.jboss.org; Jagadevan, Kamal
Subject: Re: [keycloak-dev] Same Refresh token can be used multiple times to obtain access token

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

  1.  After A1 expires, app refreshes the token pair to A2R2 USING R1
  2.  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.

Best
Kamal


________________________________
From: Stian Thorgersen <sthorger at redhat.com<mailto:sthorger at redhat.com>>
To: Marek Posolda <mposolda at redhat.com<mailto:mposolda at redhat.com>>
Cc: "Jagadevan, Kamal" <kamalakannan.jagadevan at hpe.com<mailto:kamalakannan.jagadevan at hpe.com>>; "keycloak-dev at lists.jboss.org<mailto:keycloak-dev at lists.jboss.org>" <keycloak-dev at lists.jboss.org<mailto: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<mailto: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<mailto: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><mailto:mikhail.kuznetsov at hpe.com>
To: "keycloak-dev at lists.jboss.org"<mailto:keycloak-dev at lists.jboss.org> <keycloak-dev at lists.jboss.org><mailto:keycloak-dev at lists.jboss.org>
Cc: "Jagadevan, Kamal" <kamalakannan.jagadevan at hpe.com><mailto: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<mailto: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<mailto: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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