CERT Advisory CA-2002-24 Trojan Horse OpenSSH Distribution (fwd)

From: Chris Miller (ctodd@netgate.net)
Date: 08/02/02


Date: Thu, 1 Aug 2002 17:59:57 -0700 (PDT)
From: Chris Miller <ctodd@netgate.net>
To: dinoex@FreeBSD.org


Are we affected by this? I couldn't find bf-test.c in the openssh
directory in /usr/ports. I'm assuming that since the part of the automagic
process of building the port involves checking the checksum that we are
safe, but I thought it best to ask.

Regards,
        Chris

---------- Forwarded message ----------
Date: Thu, 1 Aug 2002 17:13:46 -0400
From: CERT Advisory <cert-advisory@cert.org>
To: cert-advisory@cert.org
Subject: CERT Advisory CA-2002-24 Trojan Horse OpenSSH Distribution

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CERT Advisory CA-2002-24 Trojan Horse OpenSSH Distribution

   Original issue date: August 1, 2002
   Last revised: --
   Source: CERT/CC

   A complete revision history is at the end of this file.

Overview

   The CERT/CC has received confirmation that some copies of the source
   code for the OpenSSH package were modified by an intruder and contain
   a Trojan horse.

   We strongly encourage sites which employ, redistribute, or mirror the
   OpenSSH package to immediately verify the integrity of their
   distribution.

I. Description

   The CERT/CC has received confirmation that some copies of the source
   code for the OpenSSH package have been modified by an intruder and
   contain a Trojan horse. The following advisory has been released by
   the OpenSSH development team

          http://www.openssh.com/txt/trojan.adv

   The following files were modified to include the malicious code:

     openssh-3.4p1.tar.gz
     openssh-3.4.tgz
     openssh-3.2.2p1.tar.gz

   These files appear to have been placed on the FTP server which hosts
   ftp.openssh.com and ftp.openbsd.org on the 30th or 31st of July, 2002.
   The OpenSSH development team replaced the Trojan horse copies with the
   original, uncompromised versions at 13:00 UTC, August 1st, 2002. The
   Trojan horse copy of the source code was available long enough for
   copies to propagate to sites that mirror the OpenSSH site.

   The Trojan horse versions of OpenSSH contain malicious code that is
   run when the software is compiled. This code connects to a fixed
   remote server on 6667/tcp. It can then open a shell running as the
   user who compiled OpenSSH.

II. Impact

   An intruder operating from (or able to impersonate) the remote address
   specified in the malicious code can gain unauthorized remote access to
   any host which compiled a version of OpenSSH from this Trojan horse
   version of the source code. The level of access would be that of the
   user who compiled the source code.

III. Solution

   We encourage sites who downloaded a copy of the OpenSSH distribution
   to verify the authenticity of their distribution, regardless of where
   it was obtained. Furthermore, we encourage users to inspect any and
   all software that may have been downloaded from the compromised site.
   Note that it is not sufficient to rely on the timestamps or sizes of
   the file when trying to determine whether or not you have a copy of
   the Trojan horse version.

Where to get OpenSSH

   The primary distribution site for OpenSSH is

          http://www.openssh.com/

   Sites that mirror the OpenSSH source code are encouraged to verify the
   integrity of their sources.

Verify MD5 checksums

   You can use the following MD5 checksums to verify the integrity of
   your OpenSSH source code distribution:
   Correct versions:

     459c1d0262e939d6432f193c7a4ba8a8 openssh-3.4p1.tar.gz
     d5a956263287e7fd261528bb1962f24c openssh-3.4p1.tar.gz.sig
     39659226ff5b0d16d0290b21f67c46f2 openssh-3.4.tgz
     9d3e1e31e8d6cdbfa3036cb183aa4a01 openssh-3.2.2p1.tar.gz
     be4f9ed8da1735efd770dc8fa2bb808a openssh-3.2.2p1.tar.gz.sig

   At least one version of the modified Trojan horse distributions was
   reported to have the following checksum:
   Trojan horse version:

     3ac9bc346d736b4a51d676faa2a08a57 openssh-3.4p1.tar.gz

Verify PGP signature

   Additionally, distributions of the portable release of OpenSSH are
   distributed with detached PGP signatures. Note that the Trojan horse
   versions were not signed correctly, and attempts to verify the
   signatures would have failed.

   As a matter of good security practice, the CERT/CC encourages users to
   verify, whenever possible, the integrity of downloaded software. For
   more information, see

          http://www.cert.org/incident_notes/IN-2001-06.html

Appendix A. - Vendor Information

   This appendix contains information provided by vendors for this
   advisory. As vendors report new information to the CERT/CC, we will
   update this section and note the changes in our revision history. If a
   particular vendor is not listed below, we have not received their
   comments.

Connectiva Linux

     Conectiva Linux distributes openssh-3.4p1 as a security update. The
     distributed copy is the original one and is not affected by this
     trojan. The detached digital signature is always checked before
     building third party packages.

MandrakeSoft

     MandrakeSoft has verified that the openssh-3.4p1 sources used to
     build it's latest updates (ref. MDKSA-2002:040-1) do not contain
     this trojan.
     _________________________________________________________________
     _________________________________________________________________

   Feedback can be directed to the author: Chad Dougherty.
   ______________________________________________________________________

   This document is available from:
   http://www.cert.org/advisories/CA-2002-24.html
   ______________________________________________________________________

CERT/CC Contact Information

   Email: cert@cert.org
          Phone: +1 412-268-7090 (24-hour hotline)
          Fax: +1 412-268-6989
          Postal address:
          CERT Coordination Center
          Software Engineering Institute
          Carnegie Mellon University
          Pittsburgh PA 15213-3890
          U.S.A.

   CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) /
   EDT(GMT-4) Monday through Friday; they are on call for emergencies
   during other hours, on U.S. holidays, and on weekends.

Using encryption

   We strongly urge you to encrypt sensitive information sent by email.
   Our public PGP key is available from
   http://www.cert.org/CERT_PGP.key

   If you prefer to use DES, please call the CERT hotline for more
   information.

Getting security information

   CERT publications and other security information are available from
   our web site
   http://www.cert.org/

   To subscribe to the CERT mailing list for advisories and bulletins,
   send email to majordomo@cert.org. Please include in the body of your
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   * "CERT" and "CERT Coordination Center" are registered in the U.S.
   Patent and Trademark Office.
   ______________________________________________________________________

   NO WARRANTY
   Any material furnished by Carnegie Mellon University and the Software
   Engineering Institute is furnished on an "as is" basis. Carnegie
   Mellon University makes no warranties of any kind, either expressed or
   implied as to any matter including, but not limited to, warranty of
   fitness for a particular purpose or merchantability, exclusivity or
   results obtained from use of the material. Carnegie Mellon University
   does not make any warranty of any kind with respect to freedom from
   patent, trademark, or copyright infringement.
     _________________________________________________________________

   Conditions for use, disclaimers, and sponsorship information

   Copyright 2002 Carnegie Mellon University.

   Revision History
August 1, 2002: Initial release

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