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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2002.381 -- CERT Advisory CA-2002-24 Trojan Horse OpenSSH Distribution 2 August 2002 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: OpenSSH openssh-3.4p1.tar.gz openssh-3.4.tgz openssh-3.2.2p1.tar.gz Vendor: CERT/CC Impact: Increased Privileges Reduced Security Access Required: Remote Ref: AL-2002.10 - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- 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: firstname.lastname@example.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 email@example.com. 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 - -----BEGIN PGP SIGNATURE----- Version: PGP 6.5.8 iQCVAwUBPUmR3qCVPMXQI2HJAQFs7wP/SwypiZbfCb/FvMBgE3rFaY9Ul7vlyRKE KPncunJ+KVp2sBzTbNL01wOuASx836hTa/ByXwnX4LQLX0XzBLrDcVsrDlu1pUga Z/CopXb3KclKckmti5diCz1BNQdKbYyu/G7uHkjZQPJKC6UZr9lmge+00HMqSmHN AAOV7PQstAc= =FgfD - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to firstname.lastname@example.org and we will forward your request to the appropriate person. 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 use any or all of this information is the responsibility of each user or organisation, and should be done so in accordance with site policies and procedures. 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 original authors 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/Information/advisories.html If you believe that your system has been compromised, contact AusCERT or your representative in FIRST (Forum of Incident Response and Security Teams). Internet Email: email@example.com 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 emergencies. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBPUpdRSh9+71yA2DNAQF/vQP/SMzom4L1xGlh1d8gQO2qAK8eXvn00WEA Iya0hOeASU5DaL5GDwu7v+c7ah7YCgAhDO1Q8ieCYgnwzs0LL7XGrYb8i6kUPLNb /5WB0jP1qXPbeUODV3tK72HlnZ3OyPQoHRRpd0doQRw4W+u4+yx1CpLnnfKZK4hy ZBOPTNZgoMc= =fvhw -----END PGP SIGNATURE-----