Re: [OAUTH-WG] I-D Action: draft-ietf-oauth-token-exchange-10.txt

[Justin Richer <[e-mail]>]

+1 to Brian

-1 to the proposed text from Denis


> On Dec 8, 2017, at 8:48 PM, Brian Campbell <[e-mail]> wrote:
> 
> The privacy matter is already mentioned. Despite your many messages to this WG and others about the so called ABC attack, I do not believe it warrants treatment in this document or others. And your continued proposals to have it included in documents have not gotten support.  
> 
> On Fri, Dec 8, 2017 at 2:46 PM, Denis <[e-mail] <mailto:[e-mail]>> wrote:
> RFC 3552 (Guidelines for Writing RFC Text on Security Considerations) states: 
> 
>    All RFCs are required by RFC 2223 to contain a Security
>    Considerations section.  The purpose of this is both to encourage
>    document authors to consider security in their designs and to inform
>    the reader of relevant security issues.  This memo is intended to
>    provide guidance to RFC authors in service of both ends.
> 
> Section 5 (Writing Security Considerations Sections) of RFC 3552 states: 
> 
>    While it is not a requirement that any given protocol or system be
>    immune to all forms of attack, it is still necessary for authors to
>    consider as many forms as possible.  Part of the purpose of the
>    Security Considerations section is to explain what attacks are out of
>    scope and what countermeasures can be applied to defend against them 
> 
>    There should be a clear description of the kinds of threats on the
>    described protocol or technology.  
> 
> It is important to mention the threat related to collusion attacks. A different wording could be used, 
> but the threat should be mentioned one way or another.
> 
> RFC 6973 (Privacy Considerations for Internet Protocols) intends to provide a similar set of guidelines 
> for considering privacy in protocol design.
> 
> It is important to mention a current threat related to privacy. A different wording could be used, 
> e.g. using the word "surveillance" as mentioned in 5.1.1 : "Surveillance is the observation or monitoring 
> of an individual’s communications or activities", but the threat should be mentioned one way or another.
> 
> Denis
> 
>> I believe the text would detract from the document. 
>> From: OAuth <[e-mail]> <mailto:[e-mail]> on behalf of Brian Campbell <[e-mail]> <mailto:[e-mail]>
>> Sent: Friday, December 8, 2017 3:47:32 PM
>> To: Denis
>> Cc: oauth
>> Subject: Re: [OAUTH-WG] I-D Action: draft-ietf-oauth-token-exchange-10.txt
>>  
>> As an individual, I do not believe that the proposed text should be incorporated into the draft.
>> 
>> As one of the document editors, my responsibility is for the document to be of reasonable quality and to reflect the rough consensus of this Working Group. So I should ask the list more explicitly - are there other WG remembers who are in favor of the proposed text here (the text would have to be fixed up some too)? 
>> 
>> On Fri, Dec 1, 2017 at 11:12 AM, Denis <[e-mail] <mailto:[e-mail]>> wrote:
>> Comments on draft-ietf-oauth-token-exchange-10
>> 
>> I propose the following rephrasing for sections 6 and 7:
>> 
>> 6 . Security Considerations
>> 
>> All of the normal security issues that are discussed in [JWT],especially in relationship to comparing URIs 
>> and dealing with unrecognized values, also apply here.  In addition, both delegation and impersonation introduce 
>> unique security issues. Any time one user receives a token, the potential for abuse is a concern, 
>> since that user might be willing to collude with another user so that other user could use the token. 
>>  
>> Techniques like the binding of an access token to a TLS channel described elsewhere are ineffective since 
>> the legitimate user would be able to perform all the cryptographic computations that the other user would need 
>> to demonstrate the ownership of the token. The use of the "scp" claim is suggested to mitigate potential for 
>> such abuse, as it restricts the contexts in which the token can be exercised.  If the issued access token scope 
>> allows to unambiguously identify the user, then that user is likely to be reluctant to collude with another user.  
>> However, if the issued access token scope only indicates that the user is over 18, then there is no risk 
>> for the original user to be discovered and in such a context a collusion may easily take place. 
>> This document does not specify techniques to prevent such a collusion to be successful.
>> 
>> 7 . Privacy Considerations
>> 
>> Tokens typically carry personal information and their usage in Token Exchange may reveal details of the target services 
>> being accessed. The resource and the audience parameters allow authorization servers to know where the issued access token 
>> will be used.  This may be a privacy concern for some users. This document does not specify techniques to prevent 
>> authorization servers to know where the access tokens they issue will be used.
>> 
>> Denis
>>> 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 Token Exchange
>>>         Authors         : Michael B. Jones
>>>                           Anthony Nadalin
>>>                           Brian Campbell
>>>                           John Bradley
>>>                           Chuck Mortimore
>>> 	Filename        : draft-ietf-oauth-token-exchange-10.txt
>>> 	Pages           : 32
>>> 	Date            : 2017-11-30
>>> 
>>> Abstract:
>>>    This specification defines a protocol for an HTTP- and JSON- based
>>>    Security Token Service (STS) by defining how to request and obtain
>>>    security tokens from OAuth 2.0 authorization servers, including
>>>    security tokens employing impersonation and delegation.
>>> 
>>> 
>>> The IETF datatracker status page for this draft is:
>>> https://datatracker.ietf.org/doc/draft-ietf-oauth-token-exchange/ <https://datatracker.ietf.org/doc/draft-ietf-oauth-token-exchange/>
>>> 
>>> There are also htmlized versions available at:
>>> https://tools.ietf.org/html/draft-ietf-oauth-token-exchange-10 <https://tools.ietf.org/html/draft-ietf-oauth-token-exchange-10>
>>> https://datatracker.ietf.org/doc/html/draft-ietf-oauth-token-exchange-10 <https://datatracker.ietf.org/doc/html/draft-ietf-oauth-token-exchange-10>
>>> 
>>> A diff from the previous version is available at:
>>> https://www.ietf.org/rfcdiff?url2=draft-ietf-oauth-token-exchange-10 <https://www.ietf.org/rfcdiff?url2=draft-ietf-oauth-token-exchange-10>
>>> 
>>> 
>>> 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 <http://tools.ietf.org/>.
>>> 
>>> Internet-Drafts are also available by anonymous FTP at:
>>> ftp://ftp.ietf.org/internet-drafts/ <ftp://ftp.ietf.org/internet-drafts/>
>>> 
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>> 
>> 
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