Re: [OAUTH-WG] Call for Adoption: OAuth 2.0 Mix-Up Mitigation

[Nat Sakimura <[e-mail]>]

Interesting.
No code change even at the now compromised AS?

I can see that the phase two, the cut-and-paste attack portion works, but I
cannot see how the first portion works. Could you elaborate?
2016年1月28日(木) 5:56 Hans Zandbelt <[e-mail]>:

> a perfectly valid - at first - AS may get compromised later and used to
> attack other ASes; that attacj does not require code changes or control
> over the authorization endpoint: a rogue employee that happens to have
> access to log files (granted those include GET & POST data) on the AS
> can mount the attack if only he can phish the user
>
> we can't expect that Clients are able to judge whether an AS will become
> compromised in the future; in fact that pushes the problems to the
> really good AS who now needs to decide if it accepts Clients that are
> able to make that judgement call about other ASes that it connects to
>
> Hans.
>
> On 1/27/16 8:48 PM, Justin Richer wrote:
> > I propose we rename this the “Random ASs Attack”.
> >
> >   — Justin (only half joking)
> >
> >> On Jan 27, 2016, at 8:07 AM, Nat Sakimura <[e-mail]
> >> <mailto:[e-mail]>> wrote:
> >>
> >> Yup.
> >>
> >> For the RPs that would deal with valuable data, I also recommend it to
> >> become HTTPS only. This will effectively close the hole for the AS
> >> Mix-Up.
> >> Also, I would recommend to the clients to think twice before accepting
> >> random ASs.
> >> To prevent the code phishing, it is a good idea to require the same
> >> authority restriction. Otherwise, use some variant of discovery to get
> >> the authoritative token endpoints.
> >>
> >>
> >> 2016年1月27日(水) 21:49 George Fletcher <[e-mail]
> >> <mailto:[e-mail]>>:
> >>
> >>     Based on Hans' response to Nat I understand why this doesn't solve
> >>     all the use cases. It does still seem like a good idea from a
> >>     client perspective that would address the dynamic client
> >>     registration cases where the Bad AS is returning mixed endpoints.
> >>
> >>
> >>     On 1/27/16 7:43 AM, George Fletcher wrote:
> >>>     Following up on Nat's last paragraph... did the group in
> >>>     Darmstadt discuss this option? Namely, to require that the
> >>>     authority section of the AuthZ and Token endpoints be the same?
> >>>     Are there known implementations already deployed where the
> >>>     authority sections are different? It seems like a simple check
> >>>     that would address the endpoint mix-up cases.
> >>>
> >>>     Thanks,
> >>>     George
> >>>
> >>>     On 1/26/16 8:58 PM, Nat Sakimura wrote:
> >>>>     John,
> >>>>
> >>>>     Nov is not talking about the redirection endpoint. I just
> >>>>     noticed that 3.1.2.1 of RFC 6749 is just asking TLS by "SHOULD"
> >>>>     and I think it needs to be changed to "MUST" but that is not
> >>>>     what he is talking about.
> >>>>
> >>>>     Instead, he is talking about before starting the RFC 6749 flow.
> >>>>
> >>>>     In many cases, a non TLS protected sites have "Login with HIdP"
> >>>>     button linked to a URI that initiates the RFC 6749 flow. This
> >>>>     portion is not within  RFC 6749 and this endpoint has no name or
> >>>>     no requirement to be TLS protected. Right, it is very stupid,
> >>>>     but there are many sites like that.
> >>>>     As a result, the attacker can insert itself as a proxy, say by
> >>>>     providing a free wifi hotspot, and either re-write the button or
> >>>>     the request so that the RP receives "Login with AIdP" instead of
> >>>>     "Login with HIdP".
> >>>>
> >>>>     I have add a note explaining this to
> >>>>     <
> http://nat.sakimura.org/2016/01/15/idp-mix-up-attack-on-oauth-rfc6749/>
> http://nat.sakimura.org/2016/01/15/idp-mix-up-attack-on-oauth-rfc6749/
> >>>>
> >>>>     I also have added a bit of risk analysis on it and considered
> >>>>     other risk control measures as well.
> >>>>
> >>>>     It does not seem to be worthwhile to introduce a new
> >>>>     wire-protocol element to deal with this particular attack. (I
> >>>>     regard code cut-and-paste attack a separate attack.) I am
> >>>>     inclining to think that just to TLS protect the pre-RFC6749 flow
> >>>>     portion and add a check to disallow the ASs that has different
> >>>>     authority section for the Auhtz EP and Token EP would be adequate.
> >>>>
> >>>>     Nat
> >>>>
> >>>>     2016年1月27日(水) 2:18 John Bradley
> >>>>     <<mailto:[e-mail]>[e-mail]
> >>>>     <mailto:[e-mail]>>:
> >>>>
> >>>>         Nov,
> >>>>
> >>>>         Are you referring to Sec 3.1.2.1 of RFC 6749.
> >>>>
> >>>>         Stating that the the redirection endpoint SHOULD require
> >>>>         TLS, and that the AS should warn the user if the redirect
> >>>>         URI is not over TLS (Something I have never seen done in the
> >>>>         real world)
> >>>>
> >>>>         Not using TLS is reasonable when the redirect URI is using a
> >>>>         custom scheme for native apps.
> >>>>
> >>>>         It might almost be reasonable for the token flow where the
> >>>>         JS page itself is not loaded over TLS so the callback to
> >>>>         extract the fragment would not be as well.
> >>>>         Note that the token itself is never passed over a non https
> >>>>         connection in tis case.
> >>>>         I would argue now that it is irresponsible to have a non TLS
> >>>>         protected site, but not everyone is going to go along with
> >>>>         that.
> >>>>
> >>>>         Using a http scheme URI for the redirect is allowed but is
> >>>>         really stupid.   We did have a large debate about this when
> >>>>         profiling OAuth for Connect.
> >>>>         We did tighten connect to say that if you are using the code
> >>>>         flow then a http scheme redirect URI is only allowed if the
> >>>>         client is confidential.
> >>>>
> >>>>         John B.
> >>>>>         On Jan 26, 2016, at 1:14 AM, Phil Hunt (IDM)
> >>>>>         <[e-mail] <mailto:[e-mail]>> wrote:
> >>>>>
> >>>>>         Still don't see it. Though i think the diagram is wrong
> >>>>>         (the rp should redirct to the ua and not call the authz
> >>>>>         direct), the IDP should either return an error or redirect
> >>>>>         the RP to TLS.
> >>>>>
> >>>>>         I don't see this as proper oauth protocol since the RP is
> >>>>>         MITM the UA rather than acting as a client.
> >>>>>
> >>>>>         Phil
> >>>>>
> >>>>>         On Jan 25, 2016, at 19:57, nov matake
> >>>>>         <<mailto:[e-mail]>[e-mail]
> >>>>>         <mailto:[e-mail]>> wrote:
> >>>>>
> >>>>>>         In this flow, AuthZ endpoint is forced to be TLS-protected.
> >>>>>>
> http://nat.sakimura.org/wp-content/uploads/2016/01/oauth-idp-mixup.png
> >>>>>>
> >>>>>>         However, RP’s redirect response which causes following
> >>>>>>         AuthZ request is still not TLS-protected, and modified on
> >>>>>>         the attacker’s proxy.
> >>>>>>
> >>>>>>         Section 3.2 of this report also describes the same flow.
> >>>>>>         http://arxiv.org/pdf/1601.01229v2.pdf
> >>>>>>
> >>>>>>>         On Jan 26, 2016, at 12:37, Phil Hunt (IDM)
> >>>>>>>         <<mailto:[e-mail]>[e-mail]
> >>>>>>>         <mailto:[e-mail]>> wrote:
> >>>>>>>
> >>>>>>>         Also the authz endpoint is required to force tls. So if
> >>>>>>>         the client doesn't do it the authz should reject (eg by
> >>>>>>>         upgrading to tls).
> >>>>>>>
> >>>>>>>         Phil
> >>>>>>>
> >>>>>>>         On Jan 25, 2016, at 19:29, Phil Hunt (IDM)
> >>>>>>>         <<mailto:[e-mail]>[e-mail]
> >>>>>>>         <mailto:[e-mail]>> wrote:
> >>>>>>>
> >>>>>>>>         When the RP acting as the client issues a authorize
> >>>>>>>>         redirect to the UA it has to make it with TLS
> >>>>>>>>
> >>>>>>>>         Phil
> >>>>>>>>
> >>>>>>>>         On Jan 25, 2016, at 17:53, Nov Matake
> >>>>>>>>         <<mailto:[e-mail]>[e-mail]
> >>>>>>>>         <mailto:[e-mail]>> wrote:
> >>>>>>>>
> >>>>>>>>>         It doen't say anything about the first request which
> >>>>>>>>>         initiate the login flow.
> >>>>>>>>>         It is still a reasonable assumption that RP puts a
> >>>>>>>>>         "login with FB" button on a non TLS-protected page.
> >>>>>>>>>
> >>>>>>>>>         nov
> >>>>>>>>>
> >>>>>>>>>         On Jan 26, 2016, at 10:45, Phil Hunt
> >>>>>>>>>         <<mailto:[e-mail]>[e-mail]
> >>>>>>>>>         <mailto:[e-mail]>> wrote:
> >>>>>>>>>
> >>>>>>>>>>         I would find it hard to believe that is true.
> >>>>>>>>>>
> >>>>>>>>>>         From 6749 Sec 3.1
> >>>>>>>>>>             Since requests to the authorization endpoint result
> in user
> >>>>>>>>>>             authentication and the transmission of clear-text
> credentials (in the
> >>>>>>>>>>             HTTP response), the authorization server MUST
> require the use of TLS
> >>>>>>>>>>             as described inSection 1.6
> >>>>>>>>>>         <https://tools.ietf.org/html/rfc6749#section-1.6>
> when sending requests to the
> >>>>>>>>>>             authorization endpoint.
> >>>>>>>>>>
> >>>>>>>>>>         Sec 3.1.2.1
> >>>>>>>>>>             The redirection endpoint SHOULD require the use of
> TLS as described
> >>>>>>>>>>             inSection 1.6
> >>>>>>>>>>         <https://tools.ietf.org/html/rfc6749#section-1.6>
> when the requested response type is "code" or "token",
> >>>>>>>>>>             or when the redirection request will result in the
> transmission of
> >>>>>>>>>>             sensitive credentials over an open network.  This
> specification does
> >>>>>>>>>>             not mandate the use of TLS because at the time of
> this writing,
> >>>>>>>>>>             requiring clients to deploy TLS is a significant
> hurdle for many
> >>>>>>>>>>             client developers.  If TLS is not available, the
> authorization server
> >>>>>>>>>>             SHOULD warn the resource owner about the insecure
> endpoint prior to
> >>>>>>>>>>             redirection (e.g., display a message during the
> authorization
> >>>>>>>>>>             request).
> >>>>>>>>>>
> >>>>>>>>>>             Lack of transport-layer security can have a severe
> impact on the
> >>>>>>>>>>             security of the client and the protected resources
> it is authorized
> >>>>>>>>>>             to access.  The use of transport-layer security is
> particularly
> >>>>>>>>>>             critical when the authorization process is used as
> a form of
> >>>>>>>>>>             delegated end-user authentication by the client
> (e.g., third-party
> >>>>>>>>>>             sign-in service).
> >>>>>>>>>>
> >>>>>>>>>>         Section 10.5 talks about transmission of authorization
> >>>>>>>>>>         codes in connection with redirects.
> >>>>>>>>>>
> >>>>>>>>>>         Also see 6819, Sec 4.4.1.1 regarding eavesdropping or
> >>>>>>>>>>         leaking of authz codes.
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>         Phil
> >>>>>>>>>>
> >>>>>>>>>>         @independentid
> >>>>>>>>>>         <http://www.independentid.com/>www.independentid.com
> >>>>>>>>>>         <http://www.independentid.com/>
> >>>>>>>>>>         <mailto:[e-mail]>[e-mail]
> >>>>>>>>>>         <mailto:[e-mail]>
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>>         On Jan 25, 2016, at 4:52 PM, nov matake
> >>>>>>>>>>>         <<mailto:[e-mail]>[e-mail]
> >>>>>>>>>>>         <mailto:[e-mail]>> wrote:
> >>>>>>>>>>>
> >>>>>>>>>>>         The first assumption is coming from the original
> >>>>>>>>>>>         security report at
> >>>>>>>>>>>         <http://arxiv.org/abs/1601.01229>
> http://arxiv.org/abs/1601.01229.
> >>>>>>>>>>>
> >>>>>>>>>>>         RFC 6749 requires TLS between RS and AS, and also
> >>>>>>>>>>>         between UA and AS, but not between UA and RS.
> >>>>>>>>>>>
> >>>>>>>>>>>         The blog post is based on my Japanese post, and it
> >>>>>>>>>>>         describes multi-AS case.
> >>>>>>>>>>>         Nat's another post describes the case which can
> >>>>>>>>>>>         affect single-AS case too.
> >>>>>>>>>>>         <
> http://nat.sakimura.org/2016/01/22/code-phishing-attack-on-oauth-2-0-rfc6749/
> >
> http://nat.sakimura.org/2016/01/22/code-phishing-attack-on-oauth-2-0-rfc6749/
> >>>>>>>>>>>
> >>>>>>>>>>>         nov
> >>>>>>>>>>>
> >>>>>>>>>>>>         On Jan 26, 2016, at 08:22, Phil Hunt
> >>>>>>>>>>>>         <<mailto:[e-mail]>[e-mail]
> >>>>>>>>>>>>         <mailto:[e-mail]>> wrote:
> >>>>>>>>>>>>
> >>>>>>>>>>>>         Sorry, meant to reply-all.
> >>>>>>>>>>>>
> >>>>>>>>>>>>         Phil
> >>>>>>>>>>>>
> >>>>>>>>>>>>         @independentid
> >>>>>>>>>>>>         <http://www.independentid.com/>www.independentid.com
> >>>>>>>>>>>>         <http://www.independentid.com/>
> >>>>>>>>>>>>         <mailto:[e-mail]>[e-mail]
> >>>>>>>>>>>>         <mailto:[e-mail]>
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>>>         Begin forwarded message:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>         *From: *Phil Hunt <[e-mail]
> >>>>>>>>>>>>>         <mailto:[e-mail]>>
> >>>>>>>>>>>>>         *Subject: **Re: [OAUTH-WG] Call for Adoption: OAuth
> >>>>>>>>>>>>>         2.0 Mix-Up Mitigation*
> >>>>>>>>>>>>>         *Date: *January 25, 2016 at 3:20:19 PM PST
> >>>>>>>>>>>>>         *To: *Nat Sakimura <[e-mail]
> >>>>>>>>>>>>>         <mailto:[e-mail]>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>         I am having trouble with the very first assumption.
> >>>>>>>>>>>>>         The user-agent sets up a non TLS protected
> >>>>>>>>>>>>>         connection to the RP? That’s a fundamental
> >>>>>>>>>>>>>         violation of 6749.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>         Also, the second statement says the RP (assuming it
> >>>>>>>>>>>>>         acts as OAuth client) is talking to two IDPs.
> >>>>>>>>>>>>>         That’s still a multi-AS case is it not?
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>         Phil
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>         @independentid
> >>>>>>>>>>>>>         <http://www.independentid.com/>www.independentid.com
> <http://www.independentid.com/>
> >>>>>>>>>>>>>         <mailto:[e-mail]>[e-mail]
> >>>>>>>>>>>>>         <mailto:[e-mail]>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>>         On Jan 25, 2016, at 2:58 PM, Nat Sakimura
> >>>>>>>>>>>>>>         <<mailto:[e-mail]>[e-mail]
> >>>>>>>>>>>>>>         <mailto:[e-mail]>> wrote:
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>         Hi Phil,
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>         Since I was not in Darmstadt, I really do not know
> >>>>>>>>>>>>>>         what was discussed there, but with the compromised
> >>>>>>>>>>>>>>         developer documentation described in
> >>>>>>>>>>>>>>         <
> http://nat.sakimura.org/2016/01/15/idp-mix-up-attack-on-oauth-rfc6749/>
> http://nat.sakimura.org/2016/01/15/idp-mix-up-attack-on-oauth-rfc6749/,
> >>>>>>>>>>>>>>         all RFC6749 clients with a naive implementer will
> >>>>>>>>>>>>>>         be affected. The client does not need to be
> >>>>>>>>>>>>>>         talking to multiple IdPs.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>         Nat
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>         2016 年1月26日(火) 3:58 Phil Hunt (IDM)
> >>>>>>>>>>>>>>         <<mailto:[e-mail]>[e-mail]
> >>>>>>>>>>>>>>         <mailto:[e-mail]>>:
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>             I recall making this point in Germany. 99% of
> >>>>>>>>>>>>>>             existing use is fine. OIDC is probably the
> >>>>>>>>>>>>>>             largest community that *might* have an issue.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>             I recall proposing a new security document
> >>>>>>>>>>>>>>             that covers oauth security for dynamic
> >>>>>>>>>>>>>>             scenarios. "Dynamic" being broadly defined to
> >>>>>>>>>>>>>>             mean:
> >>>>>>>>>>>>>>             * clients who have configured at runtime or
> >>>>>>>>>>>>>>             install time (including clients that do
> discovery)
> >>>>>>>>>>>>>>             * clients that communicate with more than one
> >>>>>>>>>>>>>>             endpoint
> >>>>>>>>>>>>>>             * clients that are deployed in large volume
> >>>>>>>>>>>>>>             and may update frequently (more discussion of
> >>>>>>>>>>>>>>             "public" cases)
> >>>>>>>>>>>>>>             * clients that are script based (loaded into
> >>>>>>>>>>>>>>             browser on the fly)
> >>>>>>>>>>>>>>             * others?
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>             Phil
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>             > On Jan 25, 2016, at 10:39, George Fletcher
> >>>>>>>>>>>>>>             <<mailto:[e-mail]>[e-mail]
> >>>>>>>>>>>>>>             <mailto:[e-mail]>> wrote:
> >>>>>>>>>>>>>>             >
> >>>>>>>>>>>>>>             > would
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>             _______________________________________________
> >>>>>>>>>>>>>>             OAuth mailing list
> >>>>>>>>>>>>>>             <mailto:[e-mail]>[e-mail]
> >>>>>>>>>>>>>>             <mailto:[e-mail]>
> >>>>>>>>>>>>>>             <https://www.ietf.org/mailman/listinfo/oauth>
> https://www.ietf.org/mailman/listinfo/oauth
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>>         _______________________________________________
> >>>>>>>>>>>>         OAuth mailing list
> >>>>>>>>>>>>         <mailto:[e-mail]>[e-mail]
> >>>>>>>>>>>>         <mailto:[e-mail]>
> >>>>>>>>>>>>         <https://www.ietf.org/mailman/listinfo/oauth>
> https://www.ietf.org/mailman/listinfo/oauth
> >>>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>         _______________________________________________
> >>>>>>>>         OAuth mailing list
> >>>>>>>>         <mailto:[e-mail]>[e-mail]
> >>>>>>>>         <mailto:[e-mail]>
> >>>>>>>>         <https://www.ietf.org/mailman/listinfo/oauth>
> https://www.ietf.org/mailman/listinfo/oauth
> >>>>>>
> >>>>>         _______________________________________________
> >>>>>         OAuth mailing list
> >>>>>         [e-mail] <mailto:[e-mail]>
> >>>>>         https://www.ietf.org/mailman/listinfo/oauth
> >>>>
> >>>>         _______________________________________________
> >>>>         OAuth mailing list
> >>>>         [e-mail] <mailto:[e-mail]>
> >>>>         https://www.ietf.org/mailman/listinfo/oauth
> >>>>
> >>>>
> >>>>
> >>>>     _______________________________________________
> >>>>     OAuth mailing list
> >>>>     [e-mail] <mailto:[e-mail]>
> >>>>     https://www.ietf.org/mailman/listinfo/oauth
> >>>
> >>>     --
> >>>     Chief Architect
> >>>     Identity Services Engineering     Work:[e-mail]
> <mailto:[e-mail]>
> >>>     AOL Inc.                          AIM:  gffletch
> >>>     Mobile: [phone]           Twitter:
> http://twitter.com/gffletch
> >>>     Office: [phone]           Photos:
> http://georgefletcher.photography
> >>>     <http://georgefletcher.photography/>
> >>>
> >>>
> >>>     _______________________________________________
> >>>     OAuth mailing list
> >>>     [e-mail] <mailto:[e-mail]>
> >>>     https://www.ietf.org/mailman/listinfo/oauth
> >>
> >>     --
> >>     Chief Architect
> >>     Identity Services Engineering     Work:[e-mail]
> <mailto:[e-mail]>
> >>     AOL Inc.                          AIM:  gffletch
> >>     Mobile: [phone]           Twitter:
> http://twitter.com/gffletch
> >>     Office: [phone]           Photos:
> http://georgefletcher.photography <http://georgefletcher.photography/>
> >>
> >> _______________________________________________
> >> OAuth mailing list
> >> [e-mail] <mailto:[e-mail]>
> >> https://www.ietf.org/mailman/listinfo/oauth
> >
> >
> >
> > _______________________________________________
> > OAuth mailing list
> > [e-mail]
> > https://www.ietf.org/mailman/listinfo/oauth
> >
>
> --
> Hans Zandbelt              | Sr. Technical Architect
> [e-mail] | Ping Identity
>