Unless I’m missing something, requiring the authority section to match
discounts attackers being able to deploy executable code on a path. This kind
of hole was exploited in a number of Facebook hacks. Yes I’m aware that those
were dealing with redirect URIs but we’re talking about the same kind of
sub-component URI matching here, and I can only see it getting us into trouble.
— Justin
> On Jan 27, 2016, at 1:15 PM, Nat Sakimura <sakim...@gmail.com> wrote:
>
> yeah.
>
> But for Google, Microsoft, etc., every RP can whitelist, cannot they? ;-)
>
> Otherwise, for a code phishing attack, you need to implement discovery of
> some sort. My thinking before reading your email was:
>
> if( authority(authz_ep)==authority(token_ep) ) {
> get_token(token_ep, code, client_credential);
> } else {
> get_token(token_ep_from_discovery(), code, client_credential);
> }
>
> where token_ep_from_discovery() either returns the value of the toke_endpoint
> member from .well-known/openid-configuration OR the value of turi parameter
> in the query.
>
> 2016年1月28日(木) 2:03 Brian Campbell <bcampb...@pingidentity.com
> <mailto:bcampb...@pingidentity.com>>:
> There's at least one smallish deployment that has a different authority for
> the Authorization Endpoint and the Token Endpoint.
>
> from https://accounts.google.com/.well-known/openid-configuration
> <https://accounts.google.com/.well-known/openid-configuration> :
>
> {
> "issuer": "https://accounts.google.com <https://accounts.google.com/>",
> "authorization_endpoint": "https://accounts.google.com/o/oauth2/v2/auth
> <https://accounts.google.com/o/oauth2/v2/auth>",
> "token_endpoint": "https://www.googleapis.com/oauth2/v4/token
> <https://www.googleapis.com/oauth2/v4/token>",
> "userinfo_endpoint": "https://www.googleapis.com/oauth2/v3/userinfo
> <https://www.googleapis.com/oauth2/v3/userinfo>",
> "revocation_endpoint": "https://accounts.google.com/o/oauth2/revoke
> <https://accounts.google.com/o/oauth2/revoke>",
> "jwks_uri": "https://www.googleapis.com/oauth2/v3/certs
> <https://www.googleapis.com/oauth2/v3/certs>",
> ...
> }
>
>
> On Wed, Jan 27, 2016 at 6:30 AM, John Bradley <ve7...@ve7jtb.com
> <mailto:ve7...@ve7jtb.com>> wrote:
> It think requiring a common authority segment for the authorization endpoint
> and the token endpoint might work in common cases, but there are legitimate
> cases where the URI of the Authorization endpoint might be a alias in the
> case of multi tenants, all using a common token endpoint.
>
> The larger problem would be the RS, it is not uncommon to have the AS and RS
> in different domains, so with bearer tokens unless you make the same
> authority restriction for RS then you are not really stoping the attacker.
> They can get the AT by impersonating the RS.
>
> I think trying to enforce a common origin policy over OAuth would be a bad
> direction to go.
>
> I understand that it seems like a easy fix on the surface, and it works for
> most of the things people are using OAuth for today, but would be quite
> limiting over the long term.
>
> John B.
> > On Jan 27, 2016, at 7:31 AM, sakim...@gmail.com <mailto:sakim...@gmail.com>
> > wrote:
> >
> > Hi Hans,
> >
> > Sorry, I mixed up the IdP mix-up attack and the code phishing attack.
> >
> > Mandating the Authorization and Token Endpoint being in the same
> > authority would solve the later without changing the wire protocol.
> >
> > For AS mix-up attack, mandating the client to change the redirection
> > endpoint
> > per AS would solve the problem without change the wire protocol.
> >
> > If these are not possible, then we would have to look at changing the
> > wire protocol. The solution that solves the both cases must
> > provide the token endpoint URI authoritatively, which means
> > you have to mandate some variation of discovery mandatory.
> >
> > Nat
> >
> >
> > At 2016-01-27 17:01 Hans Zandbelt wrote:
> >> I don't see how that can deal with the specific form of the attack
> >> where the Client would have sent the authorization request to the
> >> legitimate authorization endpoint of a compromised AS and believes it
> >> gets the response from that, where in fact it was redirected away to
> >> the good AS.
> >> IOW, I don't think this is so much about mixing up endpoints where to
> >> send stuff to, but mixing up the entity/endpoint from which the Client
> >> believes the response was received. That may just be terminology
> >> though.
> >> Bottom line as far as I see is that a wire protocol element in the
> >> response is needed to tell the Client who issued it, regardless of how
> >> the Client deals with configuration of the AS information.
> >> Hans.
> >> On 1/27/16 1:31 AM, Nat Sakimura wrote:
> >>> So, is there a lot of cases that the authority section of the Good AS's
> >>> Authorization Endpoint and the Token Endpoints are different?
> >>> If not, then requiring that they are the same seems to virtually remove
> >>> the attack surface for the mix-up related attacks. It does not introduce
> >>> new parameter nor discovery. If it can be done, it probably is not worth
> >>> adding a new wire protocol element to mitigate the mix-up variants.
> >
> >
> > _______________________________________________
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> > https://www.ietf.org/mailman/listinfo/oauth
> > <https://www.ietf.org/mailman/listinfo/oauth>
>
>
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