Re: [OAUTH-WG] Mix-Up and CnP/ Code injection

Yes, and unfortunately, that is a rather common attack these days.
Infesting a user device with a malware is probably easier than having the
client developer register its client to unknown server.

2016年5月1日(日) 16:54 Torsten Lodderstedt <torsten@lodderstedt.net>:

> Hi Nat,
>
> please explain the attack. I assume the attacker would need to control
> network transmission or client device.
>
> kind regards,
> Torsten.
>
> Am 01.05.2016 um 07:36 schrieb Nat Sakimura <sakimura@gmail.com>:
>
> It actually depends on what risk level the transaction is at. For low risk
> transactions, just having separate redirection endpoint may be adequate. On
> the other hand, I can easily think of an attack that replaces iss on the
> authz response making the control invalid posing questions on whether it is
> worth introducing it.
> On Sun, May 1, 2016 at 14:21 Justin Richer <jricher@mit.edu> wrote:
>
>> I agree that we’re getting dangerously close to recommending signed
>> assertions at every step of the process, thereby bypassing HTTP. This was
>> the same mistake that WS-* and SOAP made, let’s not repeat it if we can.
>>
>>  — Justin
>>
>> On Apr 30, 2016, at 10:57 AM, Torsten Lodderstedt <
>> torsten@lodderstedt.net> wrote:
>>
>> Hi Nat,
>>
>> sure, one could also authenticate and cryptographically protect the
>> redirect response. Leveraging OIDC concepts is an idea worth considering
>> but they should be adopted to the OAuth philosophy. The id token as used in
>> the hybrid flows mixes an identity assertion with elements of transport
>> security measures. A OAuth AS does not provide identity data to clients, so
>> we only need the transport security part.
>>
>> I personally would prefer a OAuth response object (similar to request
>> object you have proposed) over the id token. Such a response object could
>> contain (and directly protect) state, code and other response values. I
>> consider this the more elegant design and it is easier to implement then
>> having detached signatures over hash values of codes or access tokens.
>> Moreover, it would allow to encrypt the response as well.
>>
>> Generally, our threat analysis so far does not have provided
>> justification for cryptographically protected redirect responses. All
>> proposals currently on the table stop mix up and code injection using
>> simpler mechanisms.
>>
>> I think OAuth 2.0 is a huge success due to its balance of versatility,
>> security and _simplicity_. We definitely need to keep it secure, but we
>> should also keep it as simple as possible.
>>
>> kind regards,
>> Torsten.
>> Am 29.04.2016 um 10:08 schrieb Nat Sakimura:
>>
>> As I look at it more and more, it started to look like the problem of
>> accepting tainted values without message authentication. To fix the root
>> cause, we would have to authenticate response. ID Token was designed to
>> also serve as a solution anticipating it.
>>
>> Any concrete ideas?
>>
>> On Sat, Apr 23, 2016 at 04:47 Torsten Lodderstedt <
>> torsten@lodderstedt.net> wrote:
>>
>>> Hi all,
>>>
>>> discussion about Mix-Up and CnP seems to have stopped after the session
>>> in BA - at least in the OAuth WG. There is a discussion about
>>> mitigations in OpenId Connect going on at the OpenId Connect mailing
>>> list.
>>>
>>> I'm very much interested to find a solution within the OAuth realm as
>>> I'm not interested to either implement two solutions (for OpenId Connect
>>> and OAuth) or adopt a OpenId-specific solution to OAuth (use id! tokens
>>> in the front channel). I therefore would like to see progress and
>>> propose to continue the discussion regarding mitigations for both
>>> threats.
>>>
>>> https://tools.ietf.org/html/draft-ietf-oauth-mix-up-mitigation-00
>>> proposes reasonable mitigations for both attacks. There are alternatives
>>> as well:
>>> - mix up:
>>> -- AS specific redirect uris
>>> -- Meta data/turi
>>> (https://tools.ietf.org/html/draft-sakimura-oauth-meta-07#section-5)
>>> - CnP:
>>> -- use of the nonce parameter (as a distinct mitigation beside state for
>>> counter XSRF)
>>>
>>> Anyone having an opinion?
>>>
>>> best regards,
>>> Torsten.
>>>
>>> _______________________________________________
>>> 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
>>
>>
>> --
Nat Sakimura
Chairman of the Board, OpenID Foundation
Trustee, Kantara Initiative