Re: Design Issue: Overlong Frames

James M Snell <jasnell@gmail.com> Fri, 10 May 2013 19:31 UTC

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From: James M Snell <jasnell@gmail.com>
Date: Fri, 10 May 2013 11:29:16 -0700
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To: Martin Thomson <martin.thomson@gmail.com>
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Subject: Re: Design Issue: Overlong Frames
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On Fri, May 10, 2013 at 10:36 AM, Martin Thomson
<martin.thomson@gmail.com> wrote:
> On 9 May 2013 10:26, James M Snell <jasnell@gmail.com> wrote:
>> Recommendation: Adding a short statement that a PROTOCOL_ERROR MUST be
>> returned if a frame contains more bytes than what is expressly
>> specified in the frame definition.
>
> That would prevent extension unnecessarily.  And it doesn't do
> anything to improve security.

How does it prevent extension? If someone wants to extend an existing
frame to include new data, it can define a new frame type.

>
> When you want to harden security, you need to consider what equivalent
> options are available to an attacker.  If I wanted to send you more
> data, then I will use DATA frames.  Unless you can find a way to
> curtail DATA I see no reason to clamp down here.

In my experience, it's generally better to limit the exploitation options ;-)

- James