e-mail tracing

["Hayden Searle" <hayden.searle () safecom co nz>]

The best way to combat these sorts of spam mailers as far as I am
concerned is to setup your email server to do PTR lookups. If the
sending domain IP doesn't match the IP where it comes from then don't
accept it and send an error back. 

For example

PTR record. <80.1.119.55> has a PTR record, but does not match HELO
string <hey.com.hk>,
Ptrs = spr1-walt1-6-0-cust55.asfd.broadband.ntl.com  

The message was sent from 80.1.119.55 which resolves to
spr1-walt1-6-0-cust55.asfd.broadband.ntl.com  but the mail says its
coming from hey.com.hk.

Most servers will do this by default anyway, you just need to enable the
option to not accept the message.

A company I support is under a spam attack and we have dropped/blocked
147,000 emails in the last 8 days....and they are one of 67 companies I
do the network security for. I hope they don't start hitting more of
them.

Regards

Hayden Searle
Network Security Specialist

-----Original Message-----
From: P S [mailto:seclistmail () hotmail com] 
Sent: Sunday, 29 August 2004 2:27 a.m.
To: security-basics () securityfocus com
Subject: e-mail tracing

Hi,
I have been getting e-mails about confirming my credit card number and
pin 
at different banks
and I decided to try to trace them back just to see where it is really 
coming from.
At school in the network security class we learnt how e-mail goes
through 
MTA's, and spammers can send e-mails through open mail servers but we
didn't 
go into details and of course they didn't give us any hands on either.

So I googled "reading e-mail headers" and went through lots of pages and

learnt a lot but I still have a few questions and I would really
apprechiate 
if somebody could help me.

What I learnt is I have to read the headers from bottom to top, thats
how it 
goes through the MTAs. Now I am reading these headers but the bottom
"from" 
lines are confusing. I will copy 3 of the headers here:

Received:
from pmta04.mta.everyone.net (bigiplb-dsnat [172.16.0.19])by 
imta41.mta.everyone.net (Postfix) with ESMTP id 7547A50809for 
<xxxx () cbgb net>; Sun, 22 Aug 2004 17:58:31 -0700 (PDT)

from 216.200.145.35 (61.149.215.9 [61.149.215.9])by
pmta04.mta.everyone.net 
(EON-PMTA) with SMTP id 894D1584for <xxxx () cbgb net>; Sun, 22 Aug 2004 
17:58:31 -0700

from E39 (a222.53.141.148.oeo6.wsj.admin170 () citibank com
[160.129.208.70])by 
mail67.k.yahoo.com

(606.70.4q95/1.773.2) with SMTP id vvh21F66RMEpjz471;Mon, 23 Aug 2004 
14:59:29 +0100


Received:
from pmta11.mta.everyone.net (bigiplb-dsnat [172.16.0.19])by 
imta39.mta.everyone.net (Postfix) with ESMTP id EC06C4A619for 
<xxxx () cbgb net>; Wed, 25 Aug 2004 13:25:59 -0700 (PDT)

from 216.200.145.35 (4.16.55.202 [4.16.55.202])by
pmta11.mta.everyone.net 
(EON-PMTA) with SMTP id F1842D83for <xxxx () cbgb net>; Wed, 25 Aug 2004 
13:25:59 -0700

from 6.190.168.160 by 4.16.55.202; Wed, 25 Aug 2004 14:23:52 -0700


Received:
from pmta08.mta.everyone.net (bigiplb-dsnat [172.16.0.19])by 
imta38.mta.everyone.net (Postfix) with ESMTP id 718FF4A636for 
<xxxx () cbgb net>; Wed, 25 Aug 2004 12:13:39 -0700 (PDT)

from x1-6-00-08-0e-8a-58-75.k149.webspeed.dk (80.162.14.71
[80.162.14.71])by 
pmta08.mta.everyone.net (EON-PMTA) with SMTP id 16ED3FB9for
<xxxx () cbgb net>; 
Wed, 25 Aug 2004 12:13:39 -0700

from 30.34.132.240 by 80.162.14.71; Wed, 25 Aug 2004 16:09:33 -0400

The first one says it's coming from 
a222.53.141.148.oeo6.wsj.admin170 () citibank com and from this I think the
IP 
address should be 148.141.53.222 but in brackets it says 160.129.208.70.

After this the received by says it was sent through yahoo's mail server.
Now 
to me it looks like this field is fake, am I right?

The second from field says 216.200.145.35 but the relaying mailserver
put in 
the real IP as 61.149.215.9. Is this the real spammer IP where the mail
is 
really coming from? Same with the other two headers, it looks like the
first 
(bottom) fields are fake. Am I right when I think the spammer sent the
mails 
from 4.16.55.202 and 80.162.14.71?

Every answer and help will be really apprechiated, thank you.

Peter

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interaction with one of our expert instructors. Gain the in-demand skills of
a certified computer examiner, learn to recover trace data left behind by
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crime and abuse so that it never happens again.

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