TUCoPS :: Unix :: General :: ca200224.txt

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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
 message
 subscribe cert-advisory
 * "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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