[oauth] Re: One-time only token exchange?

[J. Adam Moore]

I agree. "The Request Token has never been exchanged for an Access
Token." isn't explicitly saying one-time only token, but I believe
that is what was intended. Clarifying this line would be sufficient as
would requiring the Service Provider log the User out after any
request token attempt. This forces the User to login to the Service
Provider to start the process of requesting access all over.

On Apr 28, 3:13 pm, Leah Culver  wrote:
> Actually, I think it's a pretty small change to the spec.
>
> In section 6.3.2 Service Provider Grants an Access Token 
> (http://oauth.net/core/1.0/#auth_step3), it says:
>
> The Service Provider MUST ensure that:
>
>    - The request signature has been successfully verified.
>    - The Request Token has never been exchanged for an Access Token.
>    - The Request Token matches the Consumer Key.
>
> ...
> If the request fails verification or is rejected for other reasons, the
> Service Provider SHOULD respond with the appropriate response code as
> defined in HTTP Response Codes (HTTP Response
> Codes)
> .
>
> Perhaps an updated version could say something like (changes in red):
>
>  The Service Provider MUST ensure that:
>
>    - The request signature has been successfully verified.
>    - The Request Token has never been exchanged for an Access Token.
>    - There have been no prior attempts to exchange this Request Token for an
>    Access Token.
>    - The Request Token matches the Consumer Key.
>
> ...
> If the request fails verification or is rejected for other reasons, the
> Service Provider SHOULD invalidate or delete the request token and respond
> with the appropriate response code as defined in HTTP Response Codes (HTTP
> Response Codes) .
>
> On Tue, Apr 28, 2009 at 3:02 PM, Leah Culver  wrote:
>
> > Hmm... I feel like this has been lost in all the hubbub about
> > callbacks.
>
> > I strongly advocate saying something in the spec about making the
> > token exchange (access token endpoint) one-time use only.
>
> > By one-time only, I mean that the first time there is an attempt to
> > exchange a request token for an access token, if the request token has
> > not been authorized, then that request token should be marked as
> > invalid. This will make a session fixation attack nearly impossible
> > without a callback.
>
> > If a service provider allows multiple attempts to exchange the request
> > token a callback is not even necessary for the attack to work! The
> > attacker must only keep trying to exchange the token.
>
> > I know it's up to the service provider to implement one-time only
> > token exchange, but putting it in the documentation (and libraries)
> > will make it much easier for service providers to do the right thing.
>
> > Am I missing the discussion about this? Is it on the wiki and I just
> > can't find it? Or is everyone in agreement that this should be added
> > to the docs?
>
> > Thanks,
> > Leah
>
>
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[oauth] Re: How should I distinguish between approved or denied authorization?

[J. Adam Moore]

I think you send a 401 error...
http://lmgtfy.com/?q=Error+401

On Apr 27, 11:42 pm, mdub  wrote:
> Section 6.2.3 of the spec says:
>
>   If the User denies access, the Consumer MAY be notified that the
> Request Token
>   has been revoked.
>
> How does one typically indicate, in the authorization callback,
> whether the Request Token was approved or denied?
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[oauth] Re: San Francisco meetup this Tuesday 5pm

[J. Adam Moore]

I can make it.

On Apr 24, 6:12 pm, Leah Culver  wrote:
> Hey,
>
> On Fri, Apr 24, 2009 at 5:52 PM, Manish Pandit wrote:
>
>
>
>
>
> > On Apr 24, 2:42 pm, Leah Culver  wrote:
> > > Hi all,
>
> > > My eyes hurt from trying to read long email threads. There's quite a
> > > few good ideas for helping protect against the current security issue
> > > and it will be helpful to get together to discuss. Here's the details:
>
> > > OAuth Meetup
> > > Tuesday, Apr 28th at 5pm
> > > Six Apart
> > > 548 4th Street
>
> > > I'll try to get the conference call stuff working too - more about
> > > this later.
>
> > > Sorry for the short notice! I'll try to summarize the meeting and get
> > > the notes back in the mailing list or wiki.
>
> > > Leah
>
> > Thanks Leah for taking the initiative. I was wondering if some of us
> > could meet at RSA Conference at SF but since today was the last day, I
> > did not bother posting it.
>
> > It'd be great if a conference call could be worked out due to location
> > logistics, or future meetings (non-rush ones) can be done on Fridays/
> > Saturdays..
>
> > -cheers,
> > Manish
>
> We could have it this weekend instead... I'm actually pretty flexible on the
> date.
>
> Can anyone actually make it on Tuesday?
>
> Leah
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[oauth] Re: OAuth Security Advisory

[J. Adam Moore]

Yeah, I have that at my bank and it sucks all kinds of hell. Thank god
I can just Google my mother's maiden name to reset my password when
that fails. If a system is designed to work only by relying upon
people to not be stupid it will fail. You can't outwit a fool; only
fools try. I really need to finish my post on this. It has pictures
and everything. Should clear up some confusion people might have.

I am not saying that your method is forever flawed, but why change
OAuth when it works just fine? Remember, the problem we are facing is
still theoretical and the solution I proposed doesn't break anyones
current or past work or understanding.


On Apr 25, 1:33 pm, Josh Roesslein  wrote:
> The only place that a phishing attack would occur in the signed
> authorization proposal is the authorization URL.
> An attacker could lure an user to click on a link that directs the user to a
> clone of the provider and steal the users credentials
> when logging in. The best way to prevent this is users being careful to
> check the address bar and making sure the site they are at
> is indeed the provider's site. Another layer that can help prevent this is
> by using images that are displayed on the provider's site during login. Some
> banks use this during login. You first give your username and hit enter.
> Next the bank shows an image you set when you signed up. You verifty this is
> the right image and provide your password.
> This isn't really something oauth should mandate. It is up to the provider
> to add this layer of security on their own.
>
> On Sat, Apr 25, 2009 at 3:24 PM, Brian Eaton  wrote:
>
> > On Sat, Apr 25, 2009 at 1:11 PM, J. Adam Moore 
> > wrote:
> > > The problem itself is REALLY
> > > specific: Phishing. Like fish in a barrel phishing. The solution is to
> > > take away their bullets, and is not to try and harden the barrels or
> > > educate the fish to dodge bullets.
>
> > The problem is very similar to phishing, in that it requires some
> > element of social engineering to exploit.  However, the current
> > protocol allows a phishing attack where everything the user sees is
> > completely in context and true.  The session fixation vulnerability
> > allows perfect phishing.
>
> > I just reread the protocol you proposed above, and I'm pretty sure it
> > doesn't actually fix the session fixation attack.  You need some kind
> > of a callback token passed through the user's browser back to the
> > consumer.  (If you were including that, sorry, I missed it.)
>
>
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[oauth] Re: OAuth Security Advisory

[J. Adam Moore]

I think you are putting all your faith in to the security of the
information and not realizing the insecurity of the urls and
redirection. Why can't I act as a proxy for the unwitting user who
goes through your whole scenario only to find that his "secure"
authenticated token has been poached by my simply framing a consumer
site or passing your actions through cUrl requests from my site? You
are hacking away at the problem but I don't think you truly grok it.
You simply recreated it in a more complicated form. So I can't phish
you one way, but you left it wide open for everything else. I'll say
it for anyone new to the conversation: PHISHING is why we are here
discussing this. Not better encryption protocols, but implementation
people, implementation.

On Apr 25, 1:14 pm, Josh Roesslein  wrote:
> How would you phish that? Provide a step by step example.
>
> On Sat, Apr 25, 2009 at 3:11 PM, J. Adam Moore  wrote:
>
>
>
> > I could Phish the hell out of that. Pop up windows and timed out
> > requests sound like a user nightmare. Not to mention all the extra
> > checking and processing of info. It seems rather hackish. I really
> > think you are over complicating this. The problem itself is REALLY
> > specific: Phishing. Like fish in a barrel phishing. The solution is to
> > take away their bullets, and is not to try and harden the barrels or
> > educate the fish to dodge bullets.
>
> > On Apr 25, 1:01 pm, Josh Roesslein  wrote:
> > > I am not suggesting changing the entire spec, just dropping the request
> > > token part.
>
> > > This is what I'm getting at -->
> >https://oauth.pbwiki.com/Signed-Approval-URLs
>
> > > On Sat, Apr 25, 2009 at 2:58 PM, J. Adam Moore 
> > wrote:
>
> > > > EDIT LAST POST: The second "consumer" I meant to say provider.
>
> > > > On Apr 25, 12:55 pm, "J. Adam Moore"  wrote:
> > > > > What I should have added was that using my solution, the consumer is
> > > > > completely capable of being stupid and giving the consumer a redirect
> > > > > that doesn't require a login on the consumer side, but they can also
> > > > > take a gun and blow their brains out. You can't stop people from
> > being
> > > > > stupid and it's not the Providers job to even care if the redirect
> > > > > they were given is secure.
>
> > > > > I'll say it again. I AM NOT CHANGING THE OAUTH MODEL. Everything
> > works
> > > > > exactly as before EXCEPT the request token HAPPENS AFTER
> > > > > AUTHENTICATION ON THE PROVIDER SIDE. That is all. That fixes
> > > > > everything. Triggering the authentication flow AS IT IS NOW from
> > > > > behind a login ON THE PROVIDER SIDE. An attacker cannot generate a
> > > > > reusable token or spoof/calculate an access token. Totally secure
> > > > > would be the scenario I explained where both sites redirect behind a
> > > > > login. It's simple. It's easy. Lets do it.
>
> > > > > On Apr 25, 12:41 pm, "J. Adam Moore"  wrote:
>
> > > > > > Logically I find that the only way to guarantee that two different
> > > > > > users at two different sites are really the same person is to make
> > > > > > them self authenticate BEFORE establishing a secure communication.
> > By
> > > > > > having both the Provider and Consumer redirect to a spot behind a
> > > > > > login on both sites it fulfills this requirement without breaking
> > the
> > > > > > current model or people's brains. Making something simpler for the
> > > > > > sake of simplicity is simply not a compelling argument against
> > > > > > requiring habeas corpus at each end. I think too many people are
> > > > > > trying to adjust the model instead of the implementation. The model
> > is
> > > > > > fine once you can prove (on each end) that it is the same user. Not
> > > > > > caring what your login is on the consumer? What does that even
> > mean?
> > > > > > Either the redirect url is publicly accessible or it requires a
> > login.
> > > > > > I don't need to know WHO you are or care if you are logged in or
> > not,
> > > > > > but nothing is going to happen until you prove that you are who you
> > > > > > are trying to associate with. This also leaves sites able to craft
> > > > > > their redirect urls t

[oauth] Re: OAuth Security Advisory

[J. Adam Moore]

I could Phish the hell out of that. Pop up windows and timed out
requests sound like a user nightmare. Not to mention all the extra
checking and processing of info. It seems rather hackish. I really
think you are over complicating this. The problem itself is REALLY
specific: Phishing. Like fish in a barrel phishing. The solution is to
take away their bullets, and is not to try and harden the barrels or
educate the fish to dodge bullets.

On Apr 25, 1:01 pm, Josh Roesslein  wrote:
> I am not suggesting changing the entire spec, just dropping the request
> token part.
>
> This is what I'm getting at -->https://oauth.pbwiki.com/Signed-Approval-URLs
>
> On Sat, Apr 25, 2009 at 2:58 PM, J. Adam Moore  wrote:
>
>
>
> > EDIT LAST POST: The second "consumer" I meant to say provider.
>
> > On Apr 25, 12:55 pm, "J. Adam Moore"  wrote:
> > > What I should have added was that using my solution, the consumer is
> > > completely capable of being stupid and giving the consumer a redirect
> > > that doesn't require a login on the consumer side, but they can also
> > > take a gun and blow their brains out. You can't stop people from being
> > > stupid and it's not the Providers job to even care if the redirect
> > > they were given is secure.
>
> > > I'll say it again. I AM NOT CHANGING THE OAUTH MODEL. Everything works
> > > exactly as before EXCEPT the request token HAPPENS AFTER
> > > AUTHENTICATION ON THE PROVIDER SIDE. That is all. That fixes
> > > everything. Triggering the authentication flow AS IT IS NOW from
> > > behind a login ON THE PROVIDER SIDE. An attacker cannot generate a
> > > reusable token or spoof/calculate an access token. Totally secure
> > > would be the scenario I explained where both sites redirect behind a
> > > login. It's simple. It's easy. Lets do it.
>
> > > On Apr 25, 12:41 pm, "J. Adam Moore"  wrote:
>
> > > > Logically I find that the only way to guarantee that two different
> > > > users at two different sites are really the same person is to make
> > > > them self authenticate BEFORE establishing a secure communication. By
> > > > having both the Provider and Consumer redirect to a spot behind a
> > > > login on both sites it fulfills this requirement without breaking the
> > > > current model or people's brains. Making something simpler for the
> > > > sake of simplicity is simply not a compelling argument against
> > > > requiring habeas corpus at each end. I think too many people are
> > > > trying to adjust the model instead of the implementation. The model is
> > > > fine once you can prove (on each end) that it is the same user. Not
> > > > caring what your login is on the consumer? What does that even mean?
> > > > Either the redirect url is publicly accessible or it requires a login.
> > > > I don't need to know WHO you are or care if you are logged in or not,
> > > > but nothing is going to happen until you prove that you are who you
> > > > are trying to associate with. This also leaves sites able to craft
> > > > their redirect urls to contain either unique paths or unique tokens or
> > > > both without breaking the protocol or damaging the current information
> > > > exchange model. I still favor a solution that doesn't add or take away
> > > > anything from the current model. Basically a protocol that reorders
> > > > passing information to occur after user authentication and tightens
> > > > rules on where redirects point.
>
> > > > On Apr 25, 12:12 pm, Josh Roesslein  wrote:
>
> > > > > We don't really need the user to be logged into the consumer to
> > generate our
> > > > > token. The service provider should not care what our login is on the
> > > > > consumer.
> > > > > All it cares about is authorizing a consumer access to our data. We
> > log into
> > > > > the provider and authorize the creation of an access token for the
> > consumer.
> > > > > We then visit this consumer and hand over our token (either manually
> > for
> > > > > desktop apps or by being redirect by a callback w/ token attached).
> > > > > The consumer can now access our data. It is up to the consumer now on
> > how to
> > > > > store this token.  (Here is a link to the flow:
> >http://pastie.org/pastes/457478)
>
> > > > > I don't think preventing middle attacks or phis

[oauth] Re: OAuth Security Advisory

[J. Adam Moore]

EDIT LAST POST: The second "consumer" I meant to say provider.

On Apr 25, 12:55 pm, "J. Adam Moore"  wrote:
> What I should have added was that using my solution, the consumer is
> completely capable of being stupid and giving the consumer a redirect
> that doesn't require a login on the consumer side, but they can also
> take a gun and blow their brains out. You can't stop people from being
> stupid and it's not the Providers job to even care if the redirect
> they were given is secure.
>
> I'll say it again. I AM NOT CHANGING THE OAUTH MODEL. Everything works
> exactly as before EXCEPT the request token HAPPENS AFTER
> AUTHENTICATION ON THE PROVIDER SIDE. That is all. That fixes
> everything. Triggering the authentication flow AS IT IS NOW from
> behind a login ON THE PROVIDER SIDE. An attacker cannot generate a
> reusable token or spoof/calculate an access token. Totally secure
> would be the scenario I explained where both sites redirect behind a
> login. It's simple. It's easy. Lets do it.
>
> On Apr 25, 12:41 pm, "J. Adam Moore"  wrote:
>
> > Logically I find that the only way to guarantee that two different
> > users at two different sites are really the same person is to make
> > them self authenticate BEFORE establishing a secure communication. By
> > having both the Provider and Consumer redirect to a spot behind a
> > login on both sites it fulfills this requirement without breaking the
> > current model or people's brains. Making something simpler for the
> > sake of simplicity is simply not a compelling argument against
> > requiring habeas corpus at each end. I think too many people are
> > trying to adjust the model instead of the implementation. The model is
> > fine once you can prove (on each end) that it is the same user. Not
> > caring what your login is on the consumer? What does that even mean?
> > Either the redirect url is publicly accessible or it requires a login.
> > I don't need to know WHO you are or care if you are logged in or not,
> > but nothing is going to happen until you prove that you are who you
> > are trying to associate with. This also leaves sites able to craft
> > their redirect urls to contain either unique paths or unique tokens or
> > both without breaking the protocol or damaging the current information
> > exchange model. I still favor a solution that doesn't add or take away
> > anything from the current model. Basically a protocol that reorders
> > passing information to occur after user authentication and tightens
> > rules on where redirects point.
>
> > On Apr 25, 12:12 pm, Josh Roesslein  wrote:
>
> > > We don't really need the user to be logged into the consumer to generate 
> > > our
> > > token. The service provider should not care what our login is on the
> > > consumer.
> > > All it cares about is authorizing a consumer access to our data. We log 
> > > into
> > > the provider and authorize the creation of an access token for the 
> > > consumer.
> > > We then visit this consumer and hand over our token (either manually for
> > > desktop apps or by being redirect by a callback w/ token attached).
> > > The consumer can now access our data. It is up to the consumer now on how 
> > > to
> > > store this token.  (Here is a link to the 
> > > flow:http://pastie.org/pastes/457478)
>
> > > I don't think preventing middle attacks or phishing is really what oauth
> > > should be doing. SSL does this well and it should be used for the transfer
> > > of the token
> > > from the provider to the consumer. This way an attacker can't intercept 
> > > the
> > > token and use it to log in to the consumer under their account and access
> > > our data on our provider account.
>
> > > The user can't be easily phished since both URL's (authorization URL and
> > > callback URL) are verifiable by SSL. Also the callback is either stored on
> > > the service provider or signed in the authorization request by the 
> > > consumer.
>
> > > On Sat, Apr 25, 2009 at 1:43 PM, J. Adam Moore  
> > > wrote:
>
> > > > The idea is that the communication between the Consumer and Provider
> > > > sites consist of urls that are composed behind user logins ON BOTH
> > > > SITES at the same time. I believe that this prevents simpler attacks
> > > > like man in the middle or DNS or url tampering and allows secure token
> > > > generation based on session authentication, which, when empl

[oauth] Re: OAuth Security Advisory

[J. Adam Moore]

What I should have added was that using my solution, the consumer is
completely capable of being stupid and giving the consumer a redirect
that doesn't require a login on the consumer side, but they can also
take a gun and blow their brains out. You can't stop people from being
stupid and it's not the Providers job to even care if the redirect
they were given is secure.

I'll say it again. I AM NOT CHANGING THE OAUTH MODEL. Everything works
exactly as before EXCEPT the request token HAPPENS AFTER
AUTHENTICATION ON THE PROVIDER SIDE. That is all. That fixes
everything. Triggering the authentication flow AS IT IS NOW from
behind a login ON THE PROVIDER SIDE. An attacker cannot generate a
reusable token or spoof/calculate an access token. Totally secure
would be the scenario I explained where both sites redirect behind a
login. It's simple. It's easy. Lets do it.

On Apr 25, 12:41 pm, "J. Adam Moore"  wrote:
> Logically I find that the only way to guarantee that two different
> users at two different sites are really the same person is to make
> them self authenticate BEFORE establishing a secure communication. By
> having both the Provider and Consumer redirect to a spot behind a
> login on both sites it fulfills this requirement without breaking the
> current model or people's brains. Making something simpler for the
> sake of simplicity is simply not a compelling argument against
> requiring habeas corpus at each end. I think too many people are
> trying to adjust the model instead of the implementation. The model is
> fine once you can prove (on each end) that it is the same user. Not
> caring what your login is on the consumer? What does that even mean?
> Either the redirect url is publicly accessible or it requires a login.
> I don't need to know WHO you are or care if you are logged in or not,
> but nothing is going to happen until you prove that you are who you
> are trying to associate with. This also leaves sites able to craft
> their redirect urls to contain either unique paths or unique tokens or
> both without breaking the protocol or damaging the current information
> exchange model. I still favor a solution that doesn't add or take away
> anything from the current model. Basically a protocol that reorders
> passing information to occur after user authentication and tightens
> rules on where redirects point.
>
> On Apr 25, 12:12 pm, Josh Roesslein  wrote:
>
> > We don't really need the user to be logged into the consumer to generate our
> > token. The service provider should not care what our login is on the
> > consumer.
> > All it cares about is authorizing a consumer access to our data. We log into
> > the provider and authorize the creation of an access token for the consumer.
> > We then visit this consumer and hand over our token (either manually for
> > desktop apps or by being redirect by a callback w/ token attached).
> > The consumer can now access our data. It is up to the consumer now on how to
> > store this token.  (Here is a link to the 
> > flow:http://pastie.org/pastes/457478)
>
> > I don't think preventing middle attacks or phishing is really what oauth
> > should be doing. SSL does this well and it should be used for the transfer
> > of the token
> > from the provider to the consumer. This way an attacker can't intercept the
> > token and use it to log in to the consumer under their account and access
> > our data on our provider account.
>
> > The user can't be easily phished since both URL's (authorization URL and
> > callback URL) are verifiable by SSL. Also the callback is either stored on
> > the service provider or signed in the authorization request by the consumer.
>
> > On Sat, Apr 25, 2009 at 1:43 PM, J. Adam Moore  wrote:
>
> > > The idea is that the communication between the Consumer and Provider
> > > sites consist of urls that are composed behind user logins ON BOTH
> > > SITES at the same time. I believe that this prevents simpler attacks
> > > like man in the middle or DNS or url tampering and allows secure token
> > > generation based on session authentication, which, when employed
> > > properly, cannot be spoofed from either end or the middle.
>
> > > On Apr 25, 11:21 am, Josh Roesslein  wrote:
> > > > I don't really see the need for the double trip to the service provider
> > > to
> > > > perform the login and authorization.
> > > > This can be done in one single step like I have outlined in my proposal.
> > > > User logs into provider, grants access, and returns back with the token.
> > > > The less work we do in our flow 

[oauth] Re: OAuth Security Advisory

[J. Adam Moore]

Logically I find that the only way to guarantee that two different
users at two different sites are really the same person is to make
them self authenticate BEFORE establishing a secure communication. By
having both the Provider and Consumer redirect to a spot behind a
login on both sites it fulfills this requirement without breaking the
current model or people's brains. Making something simpler for the
sake of simplicity is simply not a compelling argument against
requiring habeas corpus at each end. I think too many people are
trying to adjust the model instead of the implementation. The model is
fine once you can prove (on each end) that it is the same user. Not
caring what your login is on the consumer? What does that even mean?
Either the redirect url is publicly accessible or it requires a login.
I don't need to know WHO you are or care if you are logged in or not,
but nothing is going to happen until you prove that you are who you
are trying to associate with. This also leaves sites able to craft
their redirect urls to contain either unique paths or unique tokens or
both without breaking the protocol or damaging the current information
exchange model. I still favor a solution that doesn't add or take away
anything from the current model. Basically a protocol that reorders
passing information to occur after user authentication and tightens
rules on where redirects point.

On Apr 25, 12:12 pm, Josh Roesslein  wrote:
> We don't really need the user to be logged into the consumer to generate our
> token. The service provider should not care what our login is on the
> consumer.
> All it cares about is authorizing a consumer access to our data. We log into
> the provider and authorize the creation of an access token for the consumer.
> We then visit this consumer and hand over our token (either manually for
> desktop apps or by being redirect by a callback w/ token attached).
> The consumer can now access our data. It is up to the consumer now on how to
> store this token.  (Here is a link to the 
> flow:http://pastie.org/pastes/457478)
>
> I don't think preventing middle attacks or phishing is really what oauth
> should be doing. SSL does this well and it should be used for the transfer
> of the token
> from the provider to the consumer. This way an attacker can't intercept the
> token and use it to log in to the consumer under their account and access
> our data on our provider account.
>
> The user can't be easily phished since both URL's (authorization URL and
> callback URL) are verifiable by SSL. Also the callback is either stored on
> the service provider or signed in the authorization request by the consumer.
>
> On Sat, Apr 25, 2009 at 1:43 PM, J. Adam Moore  wrote:
>
>
>
> > The idea is that the communication between the Consumer and Provider
> > sites consist of urls that are composed behind user logins ON BOTH
> > SITES at the same time. I believe that this prevents simpler attacks
> > like man in the middle or DNS or url tampering and allows secure token
> > generation based on session authentication, which, when employed
> > properly, cannot be spoofed from either end or the middle.
>
> > On Apr 25, 11:21 am, Josh Roesslein  wrote:
> > > I don't really see the need for the double trip to the service provider
> > to
> > > perform the login and authorization.
> > > This can be done in one single step like I have outlined in my proposal.
> > > User logs into provider, grants access, and returns back with the token.
> > > The less work we do in our flow the less likely an attacker can find a
> > hole.
> > > The double trip just creates a second chance for an attack.
>
> > > On Sat, Apr 25, 2009 at 12:33 PM, J. Adam Moore  > >wrote:
>
> > > > I'm writing a blog post to explain why I think I have a solution, but
> > > > I believe it is as simple as moving the provider login to before the
> > > > consumer token generation which is triggered by a provider-side
> > > > redirect. This is simply playing keep-away with redirects, but it
> > > > arguably works if your goal is web-based "sudo" permissions for an app
> > > > or site.
>
> > > > 1) User clicks on Consumer site link to Provider (no tokens or
> > > > anything, just a request for a protected area on the site that IDs the
> > > > Consumer)
> > > > 2) Link is protected, requires login. (This should generate your
> > > > session/user identifier)
> > > > 3) Once logged in user is redirected (with a unique identifier,
> > > > encrypted or not) back to a Consumer redirect page
> > > > 4) Consumer generates request t

[oauth] Re: OAuth Security Advisory

[J. Adam Moore]

The idea is that the communication between the Consumer and Provider
sites consist of urls that are composed behind user logins ON BOTH
SITES at the same time. I believe that this prevents simpler attacks
like man in the middle or DNS or url tampering and allows secure token
generation based on session authentication, which, when employed
properly, cannot be spoofed from either end or the middle.

On Apr 25, 11:21 am, Josh Roesslein  wrote:
> I don't really see the need for the double trip to the service provider to
> perform the login and authorization.
> This can be done in one single step like I have outlined in my proposal.
> User logs into provider, grants access, and returns back with the token.
> The less work we do in our flow the less likely an attacker can find a hole.
> The double trip just creates a second chance for an attack.
>
> On Sat, Apr 25, 2009 at 12:33 PM, J. Adam Moore wrote:
>
>
>
> > I'm writing a blog post to explain why I think I have a solution, but
> > I believe it is as simple as moving the provider login to before the
> > consumer token generation which is triggered by a provider-side
> > redirect. This is simply playing keep-away with redirects, but it
> > arguably works if your goal is web-based "sudo" permissions for an app
> > or site.
>
> > 1) User clicks on Consumer site link to Provider (no tokens or
> > anything, just a request for a protected area on the site that IDs the
> > Consumer)
> > 2) Link is protected, requires login. (This should generate your
> > session/user identifier)
> > 3) Once logged in user is redirected (with a unique identifier,
> > encrypted or not) back to a Consumer redirect page
> > 4) Consumer generates request token and automatically redirects back
> > to Provider's user authorization page
> > 5) User approves access, Provider automatically logs user out,
> > callbacks are optional.
> > 6) Desktop apps can use a one-time-only password-reset-style cut-n-
> > paste token IN THE NORMAL PASSWORD FIELD to authenticate.
>
> > There are many suggestions that duplicate tokens, information, or
> > steps in the process. If the initial association of the process with a
> > user is the problem, then requiring a login first will ALWAYS be the
> > solution. The flow is fine as it is, with the small exception that the
> > provider-side login requirement needs to be moved up in the process.
>
> > The game of keep-away doesn't hinge on obfuscation of the McGuffin,
> > but in passing it outside of the reach of the attacker. If an attacker
> > can use redirects to jump into the position of a player, then we can
> > use redirects to never pass the McGuffin to the same position with the
> > same info.
>
> > As far as I can tell there was only one INSIGNIFICANT flaw with OAuth
> > and that was the Provider login requirement happening too late. That's
> > it. Once you do that you can check the session or user, send nonces or
> > encrypted user_ids with the initial redirect, or just about any crazy
> > security measure you can think up.
>
> > Steps 3,4,and 5 are invisible to the user and end with a token that
> > can be used as a temporary password which triggers token authorization
> > and association with a seamless manual option that appears to jump
> > straight to step 6. Because all of this is happening behind a Provider
> > login, it is as secure as you're going to get it without fundamentally
> > changing the structure of the whole process.
>
>
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[oauth] Re: OAuth Security Advisory

[J. Adam Moore]

I'm writing a blog post to explain why I think I have a solution, but
I believe it is as simple as moving the provider login to before the
consumer token generation which is triggered by a provider-side
redirect. This is simply playing keep-away with redirects, but it
arguably works if your goal is web-based "sudo" permissions for an app
or site.

1) User clicks on Consumer site link to Provider (no tokens or
anything, just a request for a protected area on the site that IDs the
Consumer)
2) Link is protected, requires login. (This should generate your
session/user identifier)
3) Once logged in user is redirected (with a unique identifier,
encrypted or not) back to a Consumer redirect page
4) Consumer generates request token and automatically redirects back
to Provider's user authorization page
5) User approves access, Provider automatically logs user out,
callbacks are optional.
6) Desktop apps can use a one-time-only password-reset-style cut-n-
paste token IN THE NORMAL PASSWORD FIELD to authenticate.

There are many suggestions that duplicate tokens, information, or
steps in the process. If the initial association of the process with a
user is the problem, then requiring a login first will ALWAYS be the
solution. The flow is fine as it is, with the small exception that the
provider-side login requirement needs to be moved up in the process.

The game of keep-away doesn't hinge on obfuscation of the McGuffin,
but in passing it outside of the reach of the attacker. If an attacker
can use redirects to jump into the position of a player, then we can
use redirects to never pass the McGuffin to the same position with the
same info.

As far as I can tell there was only one INSIGNIFICANT flaw with OAuth
and that was the Provider login requirement happening too late. That's
it. Once you do that you can check the session or user, send nonces or
encrypted user_ids with the initial redirect, or just about any crazy
security measure you can think up.

Steps 3,4,and 5 are invisible to the user and end with a token that
can be used as a temporary password which triggers token authorization
and association with a seamless manual option that appears to jump
straight to step 6. Because all of this is happening behind a Provider
login, it is as secure as you're going to get it without fundamentally
changing the structure of the whole process.

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[oauth] Re: OAuth Security Advisory

[J. Adam Moore]

I just wrote a long post that just disappeared. Hmm. Testing...

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