Colin,
'DoNoSpoofing4From' should do it - but it is'nt. Only the first 'From:'
address is currently checked and this will not prevent this attack.
But it is possible to include 'sender: , reply-to: and errors-to:' in to
this check - which would catch this mails.
What do you think?
Thomas
Von: "Colin Waring" <co...@dolphinict.co.uk>
An: "ASSP development mailing list" <assp-test@lists.sourceforge.net>
Datum: 13.04.2018 17:17
Betreff: [Assp-test] Multiple From headers/regex based on
localdomains
Hi,
I’ve a couple of fun ones at the moment. Basically I’m getting reports of
phishing emails that get past everything.
The headers are like this:
Reply-to: Sender Name <n...@recipientdomain.tld-1.me>
To: recipi...@recipientdomain.tld
From: Sender Name <f...@domain.tld>
From: Sender Name <f...@domain2.tld>
From: Sender Name
<actualsmtpfromaddr...@legitimatebutcompromiseddomain.tld>
These bypass no spoofing as none of the from/SMTP header domains are
actually the recipient domain. Annoyingly, Outlook chooses the Reply-to
address to display so it appears almost legitimate.
I’m aware that the RFCs allow multiple from headers, though I can’t see of
any legitimate reason for this so I was considering blocking or increasing
spam score based on this – is this possible with ASSP at the moment or
not?
The second thing I was looking at doing was coming up with a regex.
Essentially, all recipient domains are in localdomains.txt so I’d want a
regex that would take all lines from localdomains. If the reply to or smtp
from address is a line from localdomains with anything else after it, then
bin it. I accept that there may in some extremely obscure cases be a clash
with a legitimate domain but do not believe that to be likely. I’ll have a
look next week as to if I can figure out a way to do it but if there’s
something obvious that you could let me know that’d be great.
All the best,
Colin.
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