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Category:   Application (E-mail Server)  >   Postfix Vendors:   Postfix.org
(EnGarde Issues Fix) Postfix Bounce Messages Let Remote Users Scan for Open Ports on Other Hosts
SecurityTracker Alert ID:  1007409
SecurityTracker URL:  http://securitytracker.com/id/1007409
CVE Reference:   CVE-2003-0468   (Links to External Site)
Date:  Aug 4 2003
Impact:   Host/resource access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 1.1.11 and prior versions
Description:   A vulnerability was reported in Postfix. A remote user can use a Postfix server to scan for open/closed ports on other hosts.

It is reported that a remote user can use a target Postfix server to conduct bounce scans of other hosts or denial of service attacks against other hosts.

A remote user can send a probing message to the following address (RCPT TO):

<[server_ip]:service!@local-host-name>

The target Postfix server will then attempt to connect to the specified port on the specified victim server. If the specified port is open, the target Postfix server will wait until the SMTP greeting timeout occurs before queueing the message. If the specified port if closed, the target Postfix server will immediately queue the message. By examining error messages eventually returned to the sender by the target Postfix server, the remote user (i.e., the sender) can determine which ports are open/closed on the specified victim server, according to the report.

The remote user can engage many Postfix servers to direct a large number of connections to a victim server to attempt a distributed denial of service attack.

Postfix versions 1.1.12 and 2.0 are reportedly not affected.

Impact:   A remote user can scan various hosts looking for open/closed ports using the Postfrix server as the scanning agent.

A remote user can attempt to conduct distributed denial of service attacks against various hosts using the Postfix server as the attack generator.

Solution:   EnGarde has released a fix. Guardian Digital Secure Network subscribers can update using their account from within the Guardian Digital WebTool.

Account information is available at:

https://www.guardiandigital.com/account/

The MD5 sums for the updated EnGarde Secure Linux 1.0.1 packages are:

SRPMS/postfix-20001121-1.0.21.src.rpm
MD5 Sum: d595e164f2e48766043486fbc71c32b8

i386/postfix-20001121-1.0.21.i386.rpm
MD5 Sum: 4402f4bb441d30c9c631a97ad843700e

i686/postfix-20001121-1.0.21.i686.rpm
MD5 Sum: 2750ae2169625dba290e80c13009f258

Vendor URL:  www.postfix.org/ (Links to External Site)
Cause:   Access control error
Underlying OS:  Linux (EnGarde)
Underlying OS Comments:  EnGarde Secure Community 1.0.1, 2; EnGarde Secure Professional 1.1, 1.2, 1.5

Message History:   This archive entry is a follow-up to the message listed below.
Aug 4 2003 Postfix Bounce Messages Let Remote Users Scan for Open Ports on Other Hosts



 Source Message Contents

Subject:  [ESA-20030804-019] 'postfix' Remote denial-of-service.


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1


+------------------------------------------------------------------------+
| Guardian Digital Security Advisory                     August 04, 2003 |
| http://www.guardiandigital.com                        ESA-20030804-019 |
|                                                                        |
| Package: postfix                                                       |
| Summary: Remote denial-of-service.                                     |
+------------------------------------------------------------------------+

  EnGarde Secure Linux is an enterprise class Linux platform engineered
  to enable corporations to quickly and cost-effectively build a complete
  and secure Internet presence while preventing Internet threats.

OVERVIEW
- --------
  Michal Zalewski has discovered a vulnerability in the Postfix MTA which
  could lead to a remote DoS attack.

  The Common Vulnerabilities and Exposures project (cve.mitre.org) has
  assigned the name CAN-2003-0540 to this issue.

  Guardian Digital products affected by this issue include:

    EnGarde Secure Community v1.0.1
    EnGarde Secure Community 2
    EnGarde Secure Professional v1.1
    EnGarde Secure Professional v1.2
    EnGarde Secure Professional v1.5

  It is recommended that all users apply this update as soon as possible.

SOLUTION
- --------
  Guardian Digital Secure Network subscribers may automatically update
  affected systems by accessing their account from within the Guardian
  Digital WebTool.

  To modify your GDSN account and contact preferences, please go to:

    https://www.guardiandigital.com/account/

  Below are MD5 sums for the updated EnGarde Secure Linux 1.0.1 packages:

    SRPMS/postfix-20001121-1.0.21.src.rpm
      MD5 Sum: d595e164f2e48766043486fbc71c32b8

    i386/postfix-20001121-1.0.21.i386.rpm
      MD5 Sum: 4402f4bb441d30c9c631a97ad843700e

    i686/postfix-20001121-1.0.21.i686.rpm
      MD5 Sum: 2750ae2169625dba290e80c13009f258

REFERENCES
- ----------
  Guardian Digital's public key:
    http://ftp.engardelinux.org/pub/engarde/ENGARDE-GPG-KEY

  Postfix's Official Web Site:
    http://www.postfix.org/

  Guardian Digital Advisories:
    http://infocenter.guardiandigital.com/advisories/

  Security Contact: security@guardiandigital.com

- --------------------------------------------------------------------------
Author: Ryan W. Maple <ryan@guardiandigital.com>
Copyright 2003, Guardian Digital, Inc.

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Version: GnuPG v1.2.2 (GNU/Linux)

iD8DBQE/LrCTHD5cqd57fu0RAkqaAJ9H21YR07MKrS/L+or68mQAXC2B7gCfabqX
4mWDMQ6LAvltRKpiNYsy3Ss=
=c2jp
-----END PGP SIGNATURE-----
------------------------------------------------------------------------
     To unsubscribe email engarde-security-request@engardelinux.org
         with "unsubscribe" in the subject of the message.

Copyright(c) 2003 Guardian Digital, Inc.             GuardianDigital.com
------------------------------------------------------------------------




 
 


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