Re: [secdir] sec-dir review of draft-ietf-sieve-autoreply-02

Derek Atkins <derek@ihtfp.com> Fri, 03 December 2010 13:46 UTC

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From: Derek Atkins <derek@ihtfp.com>
To: Barry Leiba <barryleiba@computer.org>
References: <sjmhbex9pqe.fsf@pgpdev.ihtfp.org> <AANLkTi=Lyr47Nk9EZfpZYPnvXAgp-TCj-+RHar6oSPwM@mail.gmail.com>
Date: Fri, 03 Dec 2010 08:47:34 -0500
In-Reply-To: <AANLkTi=Lyr47Nk9EZfpZYPnvXAgp-TCj-+RHar6oSPwM@mail.gmail.com> (Barry Leiba's message of "Wed, 1 Dec 2010 16:09:12 -0500")
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Cc: robinsgv@gmail.com, Alexey.Melnikov@isode.com, sieve-chairs@tools.ietf.org, iesg@ietf.org, secdir@ietf.org
Subject: Re: [secdir] sec-dir review of draft-ietf-sieve-autoreply-02
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Hi,

Barry Leiba <barryleiba@computer.org> writes:

> Hi, Derek, and thanks for the review.
>
>> The security considerations section details many potential issues with
>> automated responders.  One attack that it does not mention is the
>> potential for using the auto-responder as an oracle, in particular if
>> the system is using any public key cryptographic methods.  An attacker
>> could, theoretically, use the auto-responder to perform timing attacks.
>
> You mean, as a covert channel?
>
> The "probing" paragraph isn't sufficient to cover that as well? (It
> doesn't focus on covert channels, but does talk about probing for
> presence changes.)

I wasn't specifically thinking about covert channels.  I was more
thinking about cases where the autoresponder could perform some
operation on behalf of an attacker and return the results.  For example,
I would be concerned if the auto-responder returned the result of a DKIM
verification, or perhaps an OpenPGP or S/MIME decryption.  I'm thinking
about this more as a cryptographic oracle, not necessarily an IMPP
oracle.

> Barry

-derek

-- 
       Derek Atkins                 617-623-3745
       derek@ihtfp.com             www.ihtfp.com
       Computer and Internet Security Consultant