On Wed, 07 Jan 2009 02:06:48 -0000, MH Michael Hammer (5304) <[email protected]> wrote:
>> -----Original Message----- >> From: Jim Fenton [mailto:[email protected]] >> Sent: Tuesday, January 06, 2009 8:20 PM >> To: MH Michael Hammer (5304) >> Cc: John L; [email protected] >> Subject: Re: [ietf-dkim] Next steps for draft-ietf-dkim-ssp >> Suppose that ietf.org asserts an ADSP record but doesn't require >> signatures on incoming messages, even from its own domain (there's no >> requirement that they do). Someone spoofs a message from >> [email protected], which is of course unsigned. The message coming out > of >> the list looks like it has an author signature. I have a problem with >> that. >> > > If ietf.org is willing to put it's signature on the spoof message I > would assert that it has a DKIM problem more than an ADSP problem. Ietf is no different from any other domain. It is entitled to choose, in its ADSP policy, either 'unknown' or 'all' or 'discardable'. If it chooses 'unknown', then the list manager might adopt the (very sensible) policy of signing all list submnissions with '[email protected]' (Note that 'lists@' would probably be more sensible than Jim's original 'ietf@'. I would not expect receivers to be particularly concerned about the presence or absence of this signature, but individual recipients might like to inspect it if a message appeared suspicious. But if it chooses 'all', or even 'discardable', then the ietf chair (whose real name might be 'john') would have to arrange to submit his messages via the ietf server if he wished to use the From line '[email protected]'. More often, he would send it fron his own domain with a From line such as '[email protected]', in which case the signing policies of example.com would apply. But if his message is sent to the list, it would still attract an (additional) signature with '[email protected]'. Receivers would treat any other signature according to the example.com policies. Note that, if john did choose to use 'From: [email protected]', then it would probably attract two signatures. Moreover, if he was foolish enough to sent it via example.com's servers, then Receivers ought to be treating it with suspicion. As to whether the list manager ought to be rejecting messages that already appear bogus, that is a separate issue (though one might expect list members to be aware if his policy). It is not covered by any of our present drafts. > > Either the message has a valid signature or it does not. If there is a > valid signature then ietf.org is claiming responsibility. If it doesn't > have a valid signature....then not so much. If ietf.org is sending out > spoofed messages spoofing a "from" then it has a problem regardless of > whether it DKIM signs, uses ADSP or does anything else.. If ietf asserts 'all', and the message sent to the list by the chair using the example.com server, and which receivers _ought_ to have treated as suspicious, passes the through on account of the list manager's signature, then indeed you may have identified a valid point. But it is a point that none of our drafts covers, nor was intended to cover, so I don't see it as a reason for mucking about with it at the present time. It belongs to some future Lists draft. -- Charles H. Lindsey ---------At Home, doing my own thing------------------------ Tel: +44 161 436 6131 Web: http://www.cs.man.ac.uk/~chl Email: [email protected] snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K. PGP: 2C15F1A9 Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5 _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
