-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 In message <eb34b668-742b-4d31-af37-fed99f6f6...@fahq2.com>, Larry M. Smith <ietf....@fahq2.com> writes
>I appears to me that most of what has been discussed with regards to DKIM >replay >is an attempt to abuse systems that use DKIM for positive reputation. >However, >such replay does require that the messages pass DKIM signing. > >Hypothetically, if I were evil[1], I would sign up for a target domain's >newsletter and mutate messages with this DKIM2, and resend them. yes, although if you don't generate multiple copies this is not "DKIM replay" >While forensic >investigation would reveal the subterfuge, what gets displayed via the user's >MUA is verifiable via DKIM2 and presumably trusted. I expect overuse of >m=nomodify and this Could make the motivation for DKIM2 somewhat moot. Note that honouring "nomodify" is a matter of local policy... but if you then send the email onwards (out of your local policy space) having modified it then the system you send it to SHOULD (again they may have local policy) reject it. >An example; > >1) I sign up for email from loudmouth@political-party.example. >2) When I receive new email message I mutate them hijacking the donation >links, >maybe modify the message is subtle ways, DKIM2 sign the emails appropriately, >and resend them to my list of victims. >3) Receiving systems validate the DKIM2 and accept the messages. Yes, this is understood ... an intermediary can change an email to make it evil, and then DKIM2 sign it -- having recorded all the modifications they have made. However, their signature acknowledges that they made the changes and so it is possible to identify which intermediary (of which there may be several) made the change -- and an appropriate reputation can be assigned to that intermediary .... and not to the original sender. There's no way of determining that a change is or is not evil within the DKIM2 protocol, nor can there be. However, you do know where the evilness came from. - -- richard Richard Clayton Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Benjamin Franklin 11 Nov 1755 -----BEGIN PGP SIGNATURE----- Version: PGPsdk version 1.7.1 iQA/AwUBZ/+/wWHfC/FfW545EQJh2gCfYpEd+X2Ne6CF4od7pAI+Cb4s1doAn2cb MqaFmwwxSoZo8b8SbKEFq+6O =AOma -----END PGP SIGNATURE----- _______________________________________________ Ietf-dkim mailing list -- ietf-dkim@ietf.org To unsubscribe send an email to ietf-dkim-le...@ietf.org
