Re: ] Internet security flaw exposes private data

[Dave Farber <dfarber () me com>]

> From: "Dave CROCKER" <dcrocker () bbiw net>
> To: <dave () farber net>
> Cc: "ip" <ip () v2 listbox com>, "Peter Capek" <capek () ieee org>, "Kevin T. Neely" <ktneely () astroturfgarden com>, 
> "Charley Kline" <csk () mail com>
> Date: January 16, 2010 02:13:47 PM EST
> Subject: Re: [IP] Internet security flaw exposes private data
>
>
> Based on the limited information in the article, yes, this does smack of an 
> error in NAT-related mapping code that mis-aligns connections between clients 
> and servers (or, at least, a Facebook server.)  Although the article said 
> "misdirected cookie" it makes more sense that the entire session would be 
> mis-direction.  IP, TCP do not have special knowledge that distinguishes cookie 
> payload from other payload and the idea that HTTP code would specially mishandle 
> cookies, at the network side, would be rather strange.
>
> All of which highlights a point that was learned in the earliest days of the 
> Arpanet:  Limit how much you rely on the correctness of the underlying network 
> infrastructure.
>
> TCP's checksum is an example of that design implication, limiting its trust of 
> the underlying network's reliability.
>
> Another example was that the underlying Arpanet could misdirect a connection 
> from a host, back to itself. One effect was that the meant that the mail you 
> sent could be delivered right back to you:  The email code had no way of 
> knowing, on its own, who it had connected to.  It trusted the network.
>
> This prompted a revision so that an email server now announces its own domain 
> name, so the client can verify that it got to the right place.
>
> These are concrete examples heeding the end-to-end argument.
>
>    <http://web.mit.edu/Saltzer/www/publications/endtoend/endtoend.pdf>
>
> Similarly, Web cookies need to define their context sufficiently.  the Name of 
> their associated account (or other context declaration) needs to be embedded in 
> the cookie, in case of re-directed delivery.
>
> d/
> -- 
>
>   Dave Crocker
>   Brandenburg InternetWorking
>   bbiw.net


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