What is also should be discussed and specified is revoking of expired token. For example in Keycloak you can invalidate a session by expired token:
> It should be possible to logout a session with a token that is expired. > This is to make sure that a user can invalidate a session if there's a > suspicion that the refresh/offline token has been leaked. In such a case it > could be that the real user has an expired refresh token while an attacker > has been able to refresh the token and obtain a new not expired refresh > token. KEYCLOAK-3302 <https://issues.jboss.org/browse/KEYCLOAK-3302> Think this is doubtful but makes sense. To summarize: we have to create some threat model with description of possible use cases. On Tue, 22 May 2018 at 18:18, Sergey Ponomarev <stok...@gmail.com> wrote: > From OAuth perspective we can't say that the token should have some > structure: they can be any random value in case of reference (opaque) > tokens. But the Google's OAuth Server responds in this case with 400 error > "invalid_token". > The same can be used for JWTs with invalid sign or issuer. > So it would be better if specification allow OAuth servers to respond with > this error code if it clearly know that token was invalid by format. > > On Tue, 22 May 2018 at 17:51, Thomas Broyer <t.bro...@gmail.com> wrote: > >> IFF the server processes it! >> RFC 7009 says “An authorization server MAY ignore this parameter, >> particularly if it is able to detect the token type automatically.” which >> BTW is exactly my case. >> >> For months, my AS received requests with token=Array, and now receives >> requests with token=null. Those are clearly bugs in the client code, and >> because I return a 200 OK, the developers aren't aware of it. >> >> If tokens have an expected "structure", I think AS should probably return >> an error when the token value clearly is not a token (at one point I may >> change my implementation to do just that). As soon as it looks like a >> potential token though, then 200 OK sounds good to me. >> >> On Tue, May 22, 2018 at 4:34 PM Justin Richer <jric...@mit.edu> wrote: >> >>> In that specific case, the token_type_hint value is invalid and can be >>> rejected as an invalid_request. >>> >>> — Justin >>> >>> >>> On May 22, 2018, at 5:27 AM, Joseph Heenan <jos...@authlete.com> wrote: >>> >>> >>> I think one important point Sergey raised was that the response to the >>> client from submitting the wrong token is the same 200 response as >>> submitting a valid token, and that hugely increases the chance that the >>> developer of the client app might submit the wrong token and never realise. >>> Making it easier for the developer of the client app to see that they've >>> done something wrong and need to fix their implementation seems like a >>> worthwhile goal to me, and that would appear to explain what google are >>> thinking with their responses. >>> >>> An example of an easy to make error that would get a 200 response is >>> getting the values the wrong way around, i.e. a body of: >>> >>> token=refresh_token&token_type_hint=45ghiukldjahdnhzdauz >>> >>> (as token_type_hint may be ignored by the server.) >>> >>> The example Sergey gave of the developer accidentally sending the id >>> token instead of the intended token seems quite likely to happen in the >>> real world too, and a 200 response in that case does seem wrong to me. >>> >>> >>> Joseph >>> >>> >>> On 21 May 2018, at 22:29, Justin Richer <jric...@mit.edu> wrote: >>> >>> I’m with George here: revocation is almost a best-effort request from >>> the client’s perspective. It sends a message to the server saying “hey I’m >>> done with this token, you can throw it out too”. If the server does revoke >>> the token, the client throws it out. If the server doesn’t revoke the >>> token? Then the client still throws it out. Either way the results from the >>> client’s perspective are the same: it’s already decided that it’s done with >>> the token before it talks to the server. It’s an optional cleanup step in >>> most OAuth systems. >>> >>> — Justin >>> >>> On May 21, 2018, at 5:08 PM, George Fletcher < >>> gffletch=40aol....@dmarc.ietf.org> wrote: >>> >>> I'm not understanding how these different cases matter to the client? I >>> doubt that the running code will be able to dynamically handle the error. >>> So it seems this information is only relevant to the developers and not >>> relevant from an end user and the client perspective. >>> >>> Also, for the 5 states you define, the effect of calling revocation is >>> still that the token is "revoked" because the token is already not valid. >>> >>> So from an implementation perspective, where is the concern that >>> developer will do the "wrong thing" without these more detailed error >>> responses? >>> >>> Thanks, >>> George >>> >>> On 5/19/18 5:41 PM, Sergey Ponomarev wrote: >>> >>> Hi, >>> >>> I developing an implementation of back channel token revocation >>> endpoint. And I think we should reconsider and probably change the >>> specification to improve error handling. >>> >>> Here we see several situations of error state: >>> 1. token wasn't sent in request. >>> 2. token is invalid by format i.e. not JWT or JWT with invalid signature >>> 3. token is expired or token is even unknown >>> 4. token was already revoked >>> 5. token type is unsupported >>> >>> According to RFC7009 OAuth 2.0 Token Revocation >>> <https://tools.ietf.org/html/rfc7009> section 2.2 Revocation Response: >>> >>> The authorization server responds with HTTP status code 200 if the token >>>> has been revoked successfully or if the client submitted an invalid token. >>>> Note: invalid tokens do not cause an error response since the client >>>> cannot handle such an error in a reasonable way. Moreover, the purpose of >>>> the revocation request, invalidating the particular token, is already >>>> achieved.. >>> >>> >>> As you may see this section covers only case 3 and case 4 but it's very >>> unclear: calling token as "invalid" is very broad definition. >>> I think we should take a look on each case separately: >>> >>> 1. token wasn't sent in request. >>> Most implementations returns 400 status code, error: "invalid_request", >>> error_description": >>> "Missing required parameter: token". >>> Note that returned error is not "invalid_token" but "invalid_request" >>> and I think this should be correct behavior and should be clearly specified. >>> >>> 2. token is invalid by format i.e. not JWT or JWT with invalid signature >>> This error is mostly related to JWT but for reference (opaque) tokens >>> can be also applied (e.g. token is too long). >>> Goolge OAuth returns 400 code with "error": "invalid_token" and I think >>> this is correct behavior. >>> The client can have a bug and sends invalid tokens so we should return >>> an error response instead of 200 status. >>> >>> 3. token is expired or even unknown >>> Spec says that IdP should return 200 in this case but in case of unknown >>> token this may be a symptom of a bug on client side. Even if IdP can >>> clearly determine that token is expired (in case of JWT) this is hard to >>> determine in case of reference token that was removed from DB. >>> So personally I think that from security perspective it's better to >>> response with 400 status because client can have a bug when it's sends some >>> unknown token and think that it was revoked while it wasn't. >>> >>> For example Google OAuth revocation endpoint implementation do not >>> follow the spec and returns 400 Bad Request with error message "Token is >>> revoked or expired". >>> >>> 4. token was already revoked >>> The same as above: this can be a bug in a client and we should return >>> 400 status. In case of reference token which was removed from DB we can't >>> distinguish that the token was revoked or even existed so this situation is >>> the same as unknown token. >>> >>> 5. token type is unsupported >>> For this case specification introduces a new error code for case 5 in >>> section 2.2.1. Error Response : >>> >>>> unsupported_token_type: The authorization server does not support the >>>> revocation of the presented token type. That is, the client tried to >>>> revoke an access token on a server not supporting this feature. >>> >>> But it would be better to mention that revocation of ID token (which can >>> be is considered as "public" and not used to auth) definitely should cause >>> this error. >>> >>> It would be great if we discuss this cases and improve specification. >>> >>> P.S. Also it may be worse to mention that specification says that >>> content of successful response is empty but status code is 200 instead of >>> 201 "No Content". >>> >>> Regards, >>> Sergey Ponomarev <http://www.linkedin.com/in/stokito> >>> >>> >>> _______________________________________________ >>> OAuth mailing listOAuth@ietf.orghttps://www.ietf.org/mailman/listinfo/oauth >>> <https://www..ietf.org/mailman/listinfo/oauth> >>> >>> >>> _______________________________________________ >>> OAuth mailing list >>> OAuth@ietf.org >>> https://www.ietf.org/mailman/listinfo/oauth >>> >>> >>> _______________________________________________ >>> OAuth mailing list >>> OAuth@ietf.org >>> https://www.ietf.org/mailman/listinfo/oauth >>> >>> >>> _______________________________________________ >>> OAuth mailing list >>> OAuth@ietf.org >>> https://www.ietf.org/mailman/listinfo/oauth >>> >>> >>> _______________________________________________ >>> OAuth mailing list >>> OAuth@ietf.org >>> https://www.ietf.org/mailman/listinfo/oauth >>> >> _______________________________________________ >> OAuth mailing list >> OAuth@ietf.org >> https://www.ietf.org/mailman/listinfo/oauth >> > > > -- > Sergey Ponomarev <https://linkedin.com/in/stokito>, skype:stokito > -- Sergey Ponomarev <https://linkedin.com/in/stokito>, skype:stokito
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