Re: [OAUTH-WG] I-D Action: draft-ietf-oauth-security-topics-09.txt

Hi Torsten,

A few comments having just read this afresh:

2.1: 'Clients SHALL avoid’ - is that normatively different to ’SHOULD’ given it appears to be permitted?

I find it a little hard to understand exactly what "avoid any redirects or forwards which can be parameterized by URI query parameters” means (particularly as it comes directly after a paragraph on the redirect_uri and I initially thought it was talking about that. Perhaps something along the lines of “avoid forwarding the user’s browser to a value from a uri query parameter” might be clearer.

" Clients SHALL ensure to only process “ could just be written ‘Client SHALL only process” I think.

2.1.1:

"Authorization servers SHALL consider the”  - is ’SHALL consider’ different to ’SHOULD’? Or does it mean something like “SHALL implement at least one countermeasure from <…>”.

3.2.4:

This says "Authorization codes SHOULD be invalidated by the AS after their first use at the token endpoint”.

https://tools.ietf.org/html/rfc6749#section-10.5 says:

"Authorization codes MUST be short lived and single-use.”.

Does this "MUST be single-use” not effectively already require the code is invalidated after first use? If so why downgrade this to a “SHOULD”?

Cheers,

Joseph

> On 9 Nov 2018, at 09:42, Torsten Lodderstedt <torsten@lodderstedt.net> wrote:
> 
> Hi all, 
> 
> the new revision incorporates the recommendation to use more secure grant types instead of implicit we agreed to add during the WG session on Monday. It also has more text around justifications for our recommendation. Especially, there is a new section 3.6 on access token injection. 
> 
> I also posted about this topic on LinkedIn (https://www.linkedin.com/pulse/why-you-should-stop-using-oauth-implicit-grant-torsten-lodderstedt/) and Medium (https://medium.com/@torsten_lodderstedt/why-you-should-stop-using-the-oauth-implicit-grant-2436ced1c926)
> 
> kind regards,
> Torsten. 
> 
>> Am 09.11.2018 um 09:32 schrieb internet-drafts@ietf.org:
>> 
>> 
>> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>> This draft is a work item of the Web Authorization Protocol WG of the IETF.
>> 
>>       Title           : OAuth 2.0 Security Best Current Practice
>>       Authors         : Torsten Lodderstedt
>>                         John Bradley
>>                         Andrey Labunets
>>                         Daniel Fett
>> 	Filename        : draft-ietf-oauth-security-topics-09.txt
>> 	Pages           : 35
>> 	Date            : 2018-11-09
>> 
>> Abstract:
>>  This document describes best current security practice for OAuth 2.0.
>>  It updates and extends the OAuth 2.0 Security Threat Model to
>>  incorporate practical experiences gathered since OAuth 2.0 was
>>  published and covers new threats relevant due to the broader
>>  application of OAuth 2.0.
>> 
>> 
>> The IETF datatracker status page for this draft is:
>> https://datatracker.ietf.org/doc/draft-ietf-oauth-security-topics/
>> 
>> There are also htmlized versions available at:
>> https://tools.ietf.org/html/draft-ietf-oauth-security-topics-09
>> https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics-09
>> 
>> A diff from the previous version is available at:
>> https://www.ietf.org/rfcdiff?url2=draft-ietf-oauth-security-topics-09
>> 
>> 
>> Please note that it may take a couple of minutes from the time of submission
>> until the htmlized version and diff are available at tools.ietf.org.
>> 
>> Internet-Drafts are also available by anonymous FTP at:
>> ftp://ftp.ietf.org/internet-drafts/
>> 
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