Re: [OAUTH-WG] Comments on draft-ietf-oauth-security-topics-06.txt

[Denis <[e-mail]>]

Hi Joseph,

Among these 39 slides, to which attack(s) are you referring ?

I wrote:"It is quite hard to understand under which /context(s) /and 
conditions OAuth 2.0 could be safely used".

For each counter-measure, it would be useful to explain under which 
context(s) or under which assumptions
it should be used.

Denis

> Hi Denis,
>
>> On 22 May 2018, at 14:05, Denis <[e-mail] 
>> <mailto:[e-mail]>> wrote:
>>
>> In particular, the text states:
>>
>>        "Clients shall use PKCE [RFC7636] in order to (with the help 
>> of the authorization server) detect and prevent attempts
>>         to inject (replay) authorization codes into the authorization 
>> response".
>>
>> This is incorrect, since RFC7636 should be used when the 
>> authorization code is returned from the authorization endpoint
>> within a communication path that is _not protected_ by Transport 
>> Layer Security (TLS).
>>
> That is not really the full story as we've seen attacks where URLs 
> that you would expect to be protected by TLS are vulnerable; one 
> example is:
>
> https://www.blackhat.com/docs/us-16/materials/us-16-Kotler-Crippling-HTTPS-With-Unholy-PAC.pdf
>
> IMHO it would be sane to use PKCE anywhere where a code is returned in 
> the URL and there isn't another proof of possession / token binding 
> mechanism in play.
>
> Joseph
>