Thanks Justin, To clarify: John's comment and my question were about POST. (I do understand the behavior of HTTP POST and of window.postMessage; these are totally different things.) From my perspective in SMART Health IT, we use the OAuth 2.0 authorization code flow, including HTTP POST, in our authorization spec <http://docs.smarthealthit.org/authorization/> even for public clients, and it has worked very well for us, with about a dozen electronic health record servers supporting this approach. That's why I was curious to hear John's perspective about limitations.
-J On Fri, Jul 1, 2016 at 5:09 PM, Oleg Gryb <oleg_g...@yahoo.com> wrote: > > POST will send things to the server, which isn’t desirable if your > client is solely in the browser > Why it's not desirable, assuming that we disregard performance? You can > generate HTTP POST from JS, e.g. through an AJAX call. What is wrong with > this? > > > ------------------------------ > *From:* Justin Richer <jric...@mit.edu> > *To:* Josh Mandel <jman...@gmail.com> > *Cc:* Oleg Gryb <o...@gryb.info>; "<oauth@ietf.org>" <oauth@ietf.org>; > Liyu Yi <liy...@gmail.com> > *Sent:* Friday, July 1, 2016 2:00 PM > > *Subject:* Re: [OAUTH-WG] Security concern for URI fragment as Implicit > grant > > POST will send things to the server, which isn’t desirable if your client > is solely in the browser. postMessage is a browser API and not to be > confused with HTTP POST. postMessage messages stay (or can stay) within the > browser, which is the intent here. > > — Justin > > On Jul 1, 2016, at 4:56 PM, Josh Mandel <jman...@gmail.com> wrote: > > John, > > Could you clarify what you mean by "POST doesn't really work"? Do you > just mean that CORS support (e.g., http://caniuse.com/#feat=cors) isn't > universal, or something more? > > On Fri, Jul 1, 2016 at 4:51 PM, John Bradley <ve7...@ve7jtb.com> wrote: > > Yes but POST doesn't really work for in browser apps. > > If it is a server app it should be using the code flow with GET or POST as > you like. > > If we do a post message based binding it will be targeted at in browser > applications. > > John B. > > On Fri, Jul 1, 2016 at 4:42 PM, Liyu Yi <liy...@gmail.com> wrote: > > BTW, I do not see any significant performance concerns for post. Parsing > and executing the Javascript logic for post operation will be on the client > side, no extra server load is introduced. > > Plus post will remove the size restriction of the URL length. > > -- Liyu > > On Fri, Jul 1, 2016 at 1:35 PM, Liyu Yi <liy...@gmail.com> wrote: > > Thanks for the great comments and advices. > > I think it is a good idea for the working group to revise the fragment > part in the spec, since there might be public available tools already > implemented this approach and people can end up with a solution with > serious security loopholes. > > The re-append issue can be mitigate by a logic on Resource Server which > carefully re-writes/removes the fragment in any redirect, if the the > redirect can not be avoided. > > -- Liyu > > > On Fri, Jul 1, 2016 at 11:33 AM, John Bradley <ve7...@ve7jtb.com> wrote: > > This behaviour started changing around 2011 > > From HTTP/1.1 > See https://tools.ietf.org/html/rfc7231#section-7.1.2I > f the Location value provided in a 3xx (Redirection) response does > > not have a fragment component, a user agent MUST process the > redirection as if the value inherits the fragment component of the > URI reference used to generate the request target (i.e., the > redirection inherits the original reference's fragment, if any). > > For example, a GET request generated for the URI reference > "http://www.example.org/~tim"; might result in a 303 (See Other) > response containing the header field: > > Location: /People.html#tim > > which suggests that the user agent redirect to > "http://www.example.org/People.html#tim” > > > Likewise, a GET request generated for the URI reference > "http://www.example.org/index.html#larry"; might result in a 301 > (Moved Permanently) response containing the header field: > > Location: http://www.example.net/index.html > > which suggests that the user agent redirect to > "http://www.example.net/index.html#larry";, preserving the original > fragment identifier. > > > > This blog also explores the change. > > https://blogs.msdn.microsoft.com/ieinternals/2011/05/16/url-fragments-and-redirects/ > > > On Jul 1, 2016, at 1:05 PM, Oleg Gryb <oleg_g...@yahoo.com> wrote: > > "Browsers now re-append fragments across 302 redirects unless they are > explicitly cleared this makes fragment encoding less safe than it was when > originally specified" - thanks Jim. Looks like a good reason for vetting > this flow out. > > John, > Please provide more details/links about re-appending fragments. > > Thanks, > Oleg. > > > ------------------------------ > *From:* Jim Manico <j...@manicode.com> > *To:* Oleg Gryb <o...@gryb.info> > *Cc:* "oauth@ietf.org" <oauth@ietf.org>; Liyu Yi <liy...@gmail.com> > *Sent:* Thursday, June 30, 2016 10:25 PM > *Subject:* Re: [OAUTH-WG] Security concern for URI fragment as Implicit > grant > > Oleg! Hello! Great to see you pop up here with a similar concern. > > John Bradley just answered this thread with the details I was looking for > (thanks John, hat tip your way). > > He also mentioned details about fragment leakage: > > "Browsers now re-append fragments across 302 redirects unless they are > explicitly cleared this makes fragment encoding less safe than it was when > originally specified" > > Again, I'm new here but I'm grateful for this conversation. > > Aloha, > -- > Jim Manico > @Manicode > > On Jul 1, 2016, at 1:24 AM, Oleg Gryb <oleg_g...@yahoo.com> wrote: > > We've discussed access tokens in URI back in 2010 ( > https://www.ietf.org/mail-archive/web/oauth/current/msg04043.html). There > were two major objectives when I was saying that it's not secure: > > 1. Fragment is not sent to a server by a browser. When I've asked if this > is true for every browser in the world, nobody was able to answer. > 2. Replacing with POST would mean a significant performance impact in some > high volume implementations (I think it was Goole folks who were saying > this, but I don't remember now). > > AFAIR, nobody was arguing about browsing history, so it's valid. > > So, 6 years later we're at square one with this and I hope that this time > the community will be more successful with getting rid of secrets in URL. > > BTW, Jim, if you can come up with other scenarios when fragments can leak, > please share. It'll probably help the community with solving this problem > faster than in 6 years. > > Thanks, > Oleg. > > > ------------------------------ > *From:* Jim Manico <j...@manicode.com> > *To:* Liyu Yi <liy...@gmail.com>; oauth@ietf.org > *Sent:* Wednesday, June 29, 2016 7:30 AM > *Subject:* Re: [OAUTH-WG] Security concern for URI fragment as Implicit > grant > > > Shouldn’t it be more secure if we change to use a post method for > access token, similar to the SAML does? > I say yes. But please note I'm very new at this and someone with more > experience will have more to say or correct my comments. > Here are a few more details to consider. > 1) OAuth is a framework and not a standard, per se. Different > authorization servers will have different implementations that are not > necessarily compatible with other service providers. So there is no > standard to break, per se. > 2) Sensitive data in a URI is a bad idea. They leak all over the place > even over HTTPS. Even in fragments. > 3) Break the "rules" and find a way to submit sensitive data like access > tokens, session information or any other (even short term) sensitive data > in a secure fashion. This includes POST, JSON data payloads over PUT/PATCH > and other verbs - all over well configured HTTPS. > 4) If you really must submit sensitive data over GET , consider > JWT/JWS/JWE (with limited scopes/lifetimes) to provide message level > confidentiality and integrity. > Aloha, > > Jim Manico > Manicode Securityhttps://www.manicode.com > > > On 6/27/16 9:30 PM, Liyu Yi wrote: > > While we are working on a project with OAuth2 implementation, one question > arises from our engineers. > We noticed at <https://tools.ietf.org/html/draft-ietf-oauth-v2-31#page-30> > https://tools.ietf.org/html/draft-ietf-oauth-v2-31#page-30, it is > specified that > > (C) Assuming the resource owner grants access, the authorization > server redirects the user-agent back to the client using the > redirection URI provided earlier. The redirection URI includes > the access token in the URI fragment. > > For my understanding, the browser keeps the URI fragment in the history, > and this introduces unexpected exposure of the access token. A user without > authorization for the resource can get the access token as long as he has > the access to the browser. This can happen in a shared computer in library, > or for an IT staff who works on other employee’s computer. > > Shouldn’t it be more secure if we change to use a post method for access > token, similar to the SAML does? > I feel there might be something I missed here. Any advices will be > appreciated. > > > _______________________________________________ > OAuth mailing listOAuth@ietf.orghttps://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 > > >
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