RE: Microsoft SMTP Service

From: Colin Stefani (cstefani@tideworks.com)
Date: 07/25/01 

Message-ID: <DBC363EA37C5D311823A00508BCF2A6A07276DEA@seamail.ssofa.com>
From: Colin Stefani <cstefani@tideworks.com>
To: "'Matthew.Tim@cantire.com'" <Matthew.Tim@cantire.com>, focus-ms@securityfocus.com
Subject: RE: Microsoft SMTP Service
Date: Wed, 25 Jul 2001 13:41:51 -0700

The short answer is to block inbound SMTP sessions to that host(s) and setup
the SMTP server not to relay for other hosts, and/or not accept incoming
connections. There are a few vulnerabilities out there for MS SMTP server,
many are related to relay holes and stuff like that.

The only thing I've expressed concern about is display of internal host
names when sending. The best solution, for my networks, has been to relay
the mail through a Sendmail proxy which is configured to strip outbound
headers from the web farm machines and replace them with its own. That way
receiving hosts get mail from a known MX source (one that's listed in DNS
records) and any bouncing mail comes back either to the reply-to, from, or
host address, all of which will route back to a real mailbox.

-cs-

-----Original Message-----
From: Matthew.Tim@cantire.com [mailto:Matthew.Tim@cantire.com]
Sent: Wednesday, July 25, 2001 12:10 PM
To: focus-ms@securityfocus.com
Subject: Microsoft SMTP Service

Hello all,

Has anyone used the MS SMTP service on an IIS web server? Are there any
security risks associated with this if the server is sitting in a DMZ and
will be using this to send mail out to an external mail domain? Any help
here would be appreciated.

MT

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