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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