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Category:   Application (E-mail Server)  >   Postfix Vendors:   Postfix.org
(EnGarde Issues Fix) Postfix Address Resolver Parsing Bug Lets Remote Users Hang the System
SecurityTracker Alert ID:  1007408
SecurityTracker URL:  http://securitytracker.com/id/1007408
CVE Reference:   CVE-2003-0540   (Links to External Site)
Date:  Aug 4 2003
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 1.1.12 and prior versions
Description:   A denial of service vulnerability was reported in Postfix. A remote user may be able to cause the queue manager to lock up.

It is reported that the address parser code contains a flaw. A remote user can create a specially crafted envelope address in the SMTP header to cause the 'nqmgr' process to lock up. The exploit message's destination address must reportedly be crafted to cause a bounce (e.g., "<nonexistent@local-server-name>", "<nonexistent@[127.0.0.1]>") and the "mail from" or "Errors-To" addresses must reportedly be of the form "<.!>" or "<.!@local-server-name>". According to the report, when the code attempts to parse and rewrite the from/error address, the queue manager will lock up.

The offending message must be removed before the queue manager is restarted in order to return to normal operations.

It is also reported that a remote user can cause an instance of the SMTP listener to lock up by sending a specially crafted "RCPT TO" address of the form "<.!>" or "<.!@local-server-name>". By repeating this method, the remote user can cause denial of service conditions.

The report indicates that the system will write the following messasge to the mail log file when the flaw is triggered:

"resolve_clnt_query: null recipient"

Versions prior to 1.1.9 are not vulnerable in the default configuration, unless the 'append_dot_mydomain' setting is disabled via the configuration file.

Version 2.0 is not affected, according to the report.

The vendor was reportedly notified on July 27, 2003.

Impact:   A remote user can cause the queue manager to lock up until the exploit message is removed from the queue.

A remote user can cause a single instance of the SMTP listener to lock up until the exploit message is removed from the queue.

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:   Input validation error, State 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 Address Resolver Parsing Bug Lets Remote Users Hang the System



 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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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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