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ESB-2015.2551 - [Linux][BSD][OSX] OpenSMTPD: Execute arbitrary code/commands - Remote/unauthenticated

Date: 06 October 2015

Click here for printable version
Click here for PGP verifiable version
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Hash: SHA1

===========================================================================
             AUSCERT External Security Bulletin Redistribution

                               ESB-2015.2551
                         OpenSMTPD 5.7.2 released
                              6 October 2015

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           OpenSMTPD
Publisher:         OpenBSD
Operating System:  BSD variants
                   OS X
                   Linux variants
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                   Modify Arbitrary Files          -- Existing Account      
                   Denial of Service               -- Remote/Unauthenticated
                   Access Confidential Data        -- Remote/Unauthenticated
Resolution:        Patch/Upgrade

Original Bulletin: 
   https://www.opensmtpd.org/announces/release-5.7.2.txt

Comment: This advisory references vulnerabilities in products which run on 
         platforms other than OpenBSD. It is recommended that administrators
         running OpenSMTPD check for an updated version of the software for 
         their operating system.

- --------------------------BEGIN INCLUDED TEXT--------------------

Subject: Announce: OpenSMTPD 5.7.2 released

OpenSMTPD 5.7.2 has just been released.

OpenSMTPD is a FREE implementation of the SMTP protocol with some common
extensions. It allows ordinary machines to exchange e-mails with systems
speaking the SMTP protocol. It implements a fairly large part of RFC5321
and can already cover a large range of use-cases.

It runs on OpenBSD, NetBSD, FreeBSD, DragonFlyBSD, OSX and Linux.

The archives are now available from the main site at www.OpenSMTPD.org

We would like to thank the OpenSMTPD community for their help in testing
the snapshots, reporting bugs, contributing code and packaging for other
systems.

This is a minor release with security and reliability fixes only.
You are encouraged to update as soon as possible.

The following issues, among others less critical, were discovered during
a code audit performed by Qualys Security [https://www.qualys.com]. This
has been a very impressive and valuable contribution to our project, and
we'd like to thank them again for this ;-)


Issues fixed in this release (since 5.7.1):
===========================================

- - an oversight in the portable version of fgetln() that allows attackers
  to read and write out-of-bounds memory;

- - multiple denial-of-service vulnerabilities that allow local users to
  kill or hang OpenSMTPD;

- - a stack-based buffer overflow that allows local users to crash
  OpenSMTPD, or execute arbitrary code as the non-chrooted _smtpd user;

- - a hardlink attack (or race-conditioned symlink attack) that allows
  local users to unset the chflags() of arbitrary files;

- - a hardlink attack that allows local users to read the first line of
  arbitrary files (for example, root's hash from /etc/master.passwd);

- - a denial-of-service vulnerability that allows remote attackers to fill
  OpenSMTPD's queue or mailbox hard-disk partition;

- - an out-of-bounds memory read that allows remote attackers to crash
  OpenSMTPD, or leak information and defeat the ASLR protection;

- - a use-after-free vulnerability that allows remote attackers to crash
  OpenSMTPD, or execute arbitrary code as the non-chrooted _smtpd user;


Checksums:
==========

  SHA256 (opensmtpd-5.7.2.tar.gz) =
  e77bc57a4727233f4d725d06ccec4f89bca69fe6adabca6ee8f5683f8ac453fb

  SHA256 (opensmtpd-5.7.2p1.tar.gz) =
  daae044488d456b33aa9c84ebcc79aef2f9ab2d17ebe0c0f09e41e1f4b60d992


Verify:
=======

Starting with version 5.7.1, releases are signed with signify(1).

You can obtain the public key from our website, check with our community
that it has not been altered on its way to your machine.

Once you are confident the key is correct, you can verify the release as
described below:

1- get the signature file corresponding to the tarball you're installing

   $ wget https://www.opensmtpd.org/archives/opensmtpd-5.7.2.sum.sig


2- check that the tarball matches the checksum:

   $ sha256 opensmtpd-5.7.2.tar.gz
   SHA256 (opensmtpd-5.7.2.tar.gz) =
   e77bc57a4727233f4d725d06ccec4f89bca69fe6adabca6ee8f5683f8ac453fb
   $ cat opensmtpd-5.7.2.sum.sig |tail -1
   e77bc57a4727233f4d725d06ccec4f89bca69fe6adabca6ee8f5683f8ac453fb


3- verify that the signature file was not forged:

   $ signify -V -e -p opensmtpd.pub -m opensmtpd-5.7.2.sum
   Signature Verified


Support:
========

You are encouraged to register to our general purpose mailing-list:
    http://www.opensmtpd.org/list.html

The "Official" IRC channel for the project is at:
    #OpenSMTPD @ irc.freenode.net


Reporting Bugs:
===============

Please read http://www.opensmtpd.org/report.html
Security bugs should be reported directly to security@opensmtpd.org
Other bugs may be reported to bugs@opensmtpd.org

OpenSMTPD is brought to you by Gilles Chehade, Eric Faurot and
Sunil Nimmagadda.

- --------------------------END INCLUDED TEXT--------------------

You have received this e-mail bulletin as a result of your organisation's
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you do not know who that is, please send an email to auscert@auscert.org.au
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NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:

        http://www.auscert.org.au/render.html?cid=1980

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
===========================================================================
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