Re: [websec] WG Last Call on draft-ietf-websec-strict-transport-sec-06 until April-9

Marsh Ray <marsh@extendedsubset.com> Mon, 19 March 2012 17:05 UTC

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Date: Mon, 19 Mar 2012 12:05:04 -0500
From: Marsh Ray <marsh@extendedsubset.com>
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To: Julian Reschke <julian.reschke@gmx.de>
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Subject: Re: [websec] WG Last Call on draft-ietf-websec-strict-transport-sec-06 until April-9
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On 03/19/2012 04:35 AM, Julian Reschke wrote:
> I'd like to point out that I still think my concerns over the
> inconsistent use of quoted-string
> (<http://www.ietf.org/mail-archive/web/websec/current/msg01044.html>)
> are valid and not addressed; and I think they should be before you go to
> IETF LC.

As a developer at a company which makes a product that makes security 
decisions based on parsing HTTP headers I find Julian's concerns, well, 
concerning.

While we don't currently operate on this specific header, ambiguities in 
how an application server will interpret minor variations on header 
values often become opportunities for an attacker to bypass security 
measures. For example, a "web application firewall" (WAF) may be 
configured to forbid certain values of a customer-specified header. When 
new headers don't follow consistent syntactic rules, it takes away a bit 
of the developer's ability to simply things for his customer.

Again, I'm not claiming to be an expert on this particular header and 
clearly it's a difficult issue with arguments for doing it both ways. 
But I would ask that everyone try their best to find the least-bad 
alternative with an emphasis on consistency with the rest of HTTP.

- Marsh