e-mail tracing

From: Hayden Searle (hayden.searle_at_safecom.co.nz)
Date: 09/09/04

  • Next message: Jeffrey S. Sims: "Re[2]: learning ethical hacking"
    Date: Fri, 10 Sep 2004 03:48:50 +1200
    To: <security-basics@securityfocus.com>
    
    

    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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