Re: [OAUTH-WG] Redirection in authorization code flow: GET vs POST

Jim Manico <jim@manicode.com> Fri, 11 August 2017 20:17 UTC

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From: Jim Manico <jim@manicode.com>
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Date: Fri, 11 Aug 2017 15:17:28 -0500
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To: Josh Mandel <jmandel@gmail.com>
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Subject: Re: [OAUTH-WG] Redirection in authorization code flow: GET vs POST
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I would take it a step further. GET's leak parameters even over HTTPS. I advise all GET based OAuth communication to be switched to POST, a much more security centric verb.

Aloha,
--
Jim Manico

> On Aug 11, 2017, at 3:08 PM, Josh Mandel <jmandel@gmail.com>; wrote:
> 
> Fixing my "with this technique" url: it should have been https://gist.github.com/jmandel/4704d1efed8578a67a6f9b600ffd0c63 .
> 
>> On Fri, Aug 11, 2017 at 4:00 PM, Josh Mandel <jmandel@gmail.com>; wrote:
>> Hi All,
>> 
>> I've just encountered a server that performs a redirect (back to the client's redirect_uri) via POST instead of GET. This was surprising behavior to me and broke my client implementation — but citing chapter and verse, the server developer pointed out that https://tools.ietf.org/html/rfc6749#section-1.7 says 
>> 
>>> While the examples in this specification show the use of the HTTP 302 status code, any other method available via the user-agent to accomplish this redirection is allowed and is considered to be an implementation detail.
>> 
>> Is triggering a POST-based redirect (e.g. with this technique) to the redirect_url (including url query parameters for state and code) indeed considered a "method available via the user-agent to accomplish this redirection"? In other words, should a well-behaved OAuth client be prepared to receive GETs as well as POSTs to its redirect_uri? If so, what would be the considerations for a server choosing between GET and POST?
>> 
>> Best,
>> 
>>   Josh
> 
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