Re: email address "spoofed"

["Webb Wang CS" <webb.wang () cybershieldnetworks com>]

Tim,

Feels like your SMTP server got open relay enabled.

Just by examining your message header, it reported message was from your
email server.

Depending on your server setting, anybody can manually telnet to your server
on port 25 and craft out a message with fake 'from' field and have it sent
out to a legit account.

To close up this hole, we usually do one or more of the following:
(1) disable open relay feature at the server
(2) require authentication on user account before allowing message sending
(3) make sure a successful email retrieval (or POP) before allowing sending
message with the user account
(4) force a DNS reverse look up to ensure the remote site has a legit DNS
record.

My 2 cents,

Webb
----



I'm not sure if "spoofing" is the correct term but here is what has
happened:

Someone is sending out email messages (with virus laden attachments)
using our domain name  ... they are addressed as coming from
support () ourdomainname com (ourdomainame would be our actual domain name)
which is an email address that we never set up.

My question is how is this done and is there anything we can do to
prevent this in the future?  The message header looks like this:

Received: from your-xhtr8hvc4p [68.55.1.207] by ourdomainname.com
  (SMTPD32-8.05) id A3C8DF0118; Fri, 05 Mar 2004 04:09:28 -0500
Date: Fri, 05 Mar 2004 04:07:07 -0500
To: info () ourdomainname com
Subject: E-mail account security warning.
From: support () ourdomainname com
Message-ID: <oruybbfoofisdsegtve () ourdomainname com>
MIME-Version: 1.0
Content-Type: multipart/mixed;
        boundary="--------hggfurquvkrsejwodibt"
X-RCPT-TO: <info () ourdomainname com>
Status: U
X-UIDL: 355598192


Tim




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to facilitate one-on-one interaction with one of our expert instructors. 
Attend a course taught by an expert instructor with years of in-the-field 
pen testing experience in our state of the art hacking lab. Master the skills 
of an Ethical Hacker to better assess the security of your organization. 
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