Re: [OAUTH-WG] Ignoring unrecognized request parameters

Eran Hammer <> Thu, 16 February 2012 23:01 UTC

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From: Eran Hammer <>
To: John Bradley <>, William Mills <>
Date: Thu, 16 Feb 2012 16:01:46 -0700
Thread-Topic: [OAUTH-WG] Ignoring unrecognized request parameters
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Subject: Re: [OAUTH-WG] Ignoring unrecognized request parameters
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Can you give an example where an unknown parameter being ignored can lead to security issues?


From: John Bradley <<>>
Date: Thu, 16 Feb 2012 11:55:21 -0700
To: William Mills <<>>
Cc: "<>" <<>>
Subject: Re: [OAUTH-WG] Ignoring unrecognized request parameters

If you have a generic client that works across multiple Authorization endpoints some that have extension X and others not, I can see that having the Authorization servers ignore unknown parameters is desirable.

However there are some endpoints that are not going to be able to allow unknown parameters due to there security policy.   They are often a indication of an attack.

If this remains a MUST then some endpoints will have to ignore it, and be non compliant.

I would be OK with something like "MUST ignore unknown parameters unless the endpoint is required to return an error due to local security policy."

There is probably no perfect compromise on this one.

John B.

On 2012-02-16, at 3:32 PM, William Mills wrote:

No, this is required for forward compatibility.  Implementations that send extended parameters like capability advertisements (i.e. CAPTCHA support or something) shoudl not be broken hitting older implementations.

From: Mike Jones <<>>
To: "<>" <<>>
Sent: Thursday, February 16, 2012 10:16 AM
Subject: [OAUTH-WG] Ignoring unrecognized request parameters

In core -23, the last paragraph of section 3.1<> now says:

                The authorization server MUST ignore unrecognized request parameters.

In -22, this said:

                The authorization server SHOULD ignore unrecognized request parameters.

In a security protocol, it seems unreasonable to require that information be ignored.  As I see it, it SHOULD be legal to return an error if unrecognized information is received.

Why the change?  And can we please have it changed back to SHOULD in -24?

                                                                -- Mike

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