__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Center ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN OpenSSH Contains Remotely Exploitable Vulnerability [Pine Internet Security Advisory 20020301] March 7, 2002 18:00 GMT Number M-054 ______________________________________________________________________________ PROBLEM: A remotely exploitable vulnerability has been identified in the channel code of OpenSSH. PLATFORM: All platforms using OpenSSH versions prior to version 3.1. DAMAGE: Users with an existing account could upgrade privileges, up to and including root. Exploitability without an existing user account has not been proven but is not considered impossible. A malicious ssh server could also use this vulnerability to exploit a connecting vulnerable client. SOLUTION: CIAC recommends that you upgrade to version 3.1 or apply the included patch. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. Exploitability without an existing user ASSESSMENT: account has not been proven. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/m-054.shtml ORIGINAL BULLETIN: http://www.pine.nl/advisories/pine-cert-20020301.txt PATCHES: http://www.openssh.com http://www.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh http://www.pine.nl/advisories/pine-cert-20020301.patch ______________________________________________________________________________ [***** Start Pine Internet Security Advisory 20020301 *****] ----------------------------------------------------------------------------- Pine Internet Security Advisory ----------------------------------------------------------------------------- Advisory ID : PINE-CERT-20020301 Authors : Joost Pol Issue date : 2002-03-07 Application : OpenSSH Version(s) : All versions between 2.0 and 3.0.2 Platforms : multiple Vendor informed : 20020304 Availability : http://www.pine.nl/advisories/pine-cert-20020301.txt ----------------------------------------------------------------------------- Synopsis A bug exists in the channel code of OpenSSH versions 2.0 - 3.0.2 Users with an existing user account can abuse this bug to gain root privileges. Exploitability without an existing user account has not been proven but is not considered impossible. A malicious ssh server could also use this bug to exploit a connecting vulnerable client. Impact HIGH: Existing users will gain root privileges. Description Simple off by one error. Patch included. Solution The OpenSSH project will shortly release version 3.1. Upgrading to this version is highly recommended. This version will be made available at http://www.openssh.com The FreeBSD port of OpenSSH has been updated to reflect the patches as supplied in this document. OpenSSH CVS has been updated, see: OpenBSD cvs entry for channels.c at http://www.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/channels.c.diff?r1=1.170&r2=1.171 Or apply the attached patch as provided by PINE Internet: http://www.pine.nl/advisories/pine-cert-20020301.patch [***** End Pine Internet Security Advisory 20020301 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Pine CERT for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Center, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. 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