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

[Kuznetsov, Mike]

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<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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