nanog mailing list archives

Re: Microsoft O365 labels nanog potential fraud?


From: Alan Hodgson <ahodgson () lists simkin ca>
Date: Wed, 29 Mar 2017 15:03:20 -0700

On Wednesday 29 March 2017 14:28:30 Carl Byington wrote:
For an example of that (unless I am misunderstanding something), we
have:

 --> Hello marketo-email.box.com [192.28.147.169], pleased to meet you
 <-- MAIL FROM:<$MUNGED () marketo-email box com>
 <-- RCPT TO: ...

dkim pass header.d=mktdns.com
rfc2822 from header = $MUNGED () email box com


dig _dmarc.email.box.com txt +short
"v=DMARC1; p=reject; ..."

dig email.box.com txt +short
"v=spf1 ip4:192.28.147.168 -all"

So given the dmarc reject policy, it needs to pass either spf (which
fails 192.28.147.168 != 192.28.147.169), or dkim (which fails since it
is not signed by anything related to email.box.com.

Am I missing something, or is that just broken?

That appears to be broken. The -all on the SPF record alone breaks it, since 
receivers should refuse it at that point. But yeah the DMARC is also broken.

Interestingly, the mail I've seen recently from email.box.com has multiple 
signatures, one of which is from email.box.com. And it originated from 
192.28.147.168. Weird.


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