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SuSE: SA:2000:47 Moderate: Openssh Clientside Remote Access Risk

Many vulnerabilities have been found in the openssh package, along with a compilation problem in the openssh and ssh packages in the SuSE-7.0 distribution.. -----BEGIN PGP SIGNED MESSAGE----- ______________________________________________________________________________ SuSE Security Announcement Package: openssh/ssh Announcement-ID: SuSE-SA:2000:47 Date: Friday, November 24th, 2000 16:30 MET Affected SuSE versions: 6.4, 7.0 Vulnerability Type: clientside remote vulnerability Severity (1-10): 6 SuSE default package: yes Other affected systems: systems w/ openssh versions before 2.3.0 Content of this advisory: 1) security vulnerability resolved: openssh problem description, discussion, solution and upgrade information 2) pending vulnerabilities, solutions, workarounds 3) standard appendix (further information) ______________________________________________________________________________ 1) problem description, brief discussion, solution, upgrade information openssh is an implementation of the secure shell protocol, available under the BSD license, primarily maintained by the OpenBSD Project. Many vulnerabilities have been found in the openssh package, along with a compilation problem in the openssh and ssh packages in the SuSE-7.0 distribution: An openssh client (the ssh program) can accept X11- or ssh-agent forwarding requests even though these forwarding capabilities have not been requested by the client side after successful authentication. Using these weaknesses, an attacker could gain access to the authentication agent which may hold multiple user-owned authentification identities, or to the X-server on the client side as if requested by the user. These problems have been found/reported by Markus Friedl and Jacob Langseth . A problem in theconfigure script in both the openssh and ssh package on the SuSE-7.0 distribution caused the sshd programs to not be linked against the tcp-wrapper library. By consequence, access rules for the sshd server-side service as configured in /etc/hosts.allow and /etc/hosts.deny were ignored. This has been reported to us by Lutz Pressler . We thank these individuals for their contribution. Sebastian Krahmer found a small tmp file handling problem in the perl script `make-ssh-known-hosts´. A (local) attacker could trick the perl program to follow symbolic links and thereby overwriting files with the privileges of the user calling make-ssh-known-hosts. The solution for the first three problems (agent+X11-forwarding, missing libwrap support) is an upgrade to a newer package. The tmp file problem can be easily solved by hand. Please see the special install instructions below. Note: Upon public request, we also provide update packages for the SuSE-6.3 Intel distribution, even though the openssh packages was not included in this distribution. special install instructions: ==================================== To find out which package (ssh or openssh) you use, please use the command `rpm -qf /usr/bin/ssh´. __ case openssh: Please follow the instructions below to download and install the update package. Afterwards, restart the sshd daemon: `rcsshd restart´. __ case ssh: before SuSE-7.0 (excluding 7.0): In the file /usr/bin/make-ssh-known-hosts, please change the line (around line 102) $private_ssh_known_hosts = "/tmp/ssh_known_hosts$$"; to read $private_ssh_known_hosts = "~/ssh_known_hosts$$"; and you are done. SuSE-7.0: Please follow the instructions below to download and install the update package. Afterwards, restart the sshd daemon: `rcsshd restart´ Please choose the update package(s) for your distribution from the URLs listed below and download the necessary rpm files. Then, install the package using the command `rpm -Uhv file.rpm´. rpm packages have an internal md5 checksum that protects against file corruption. You can verify this checksum using the command (independently from the md5 signatures below) `rpm --checksig --nogpg file.rpm', The md5 sums under each package are to prove the package authenticity, independently from the md5 checksums in the rpm package format. i386 Intel Platform: SuSE-7.0 3c7b9044ffb64f9f74c904eb2b278eb2 source rpm: aebcda19518208497671e752bbdfaeb8 SuSE-6.4 04c17b0eba99c798ae401fb9aafbc7e4 source rpm: 2003ab41cfa32ef39b11b4977ef4cd1f SuSE-6.3 04c17b0eba99c798ae401fb9aafbc7e4 source rpm: 2003ab41cfa32ef39b11b4977ef4cd1f Sparc Platform: SuSE-7.0 898aaaacee88777429496f1a5658076f source rpm: 97868b04de04a0baafcee69ebbbe6079 AXP Alpha Platform: SuSE-7.0 dd12c60b2744455780c976b115b26f27 source rpm: 6df5af1a88fda4d8fc1a493e4d10bc01 SuSE-6.4 99de4bb6f183be1b69a610744f4566bc source rpm: aa56e311205ba58478c815760452367e PPC Power PC Platform: SuSE-7.0 72f7c339991e54a476585012423dda62 source rpm: 749ccc55396944ad43c1977e55903958 SuSE-6.4 59727fa055e5d835bc4e455302b1ef49 source rpm: 7e42dbad4e50a2ad9156e94cf2a93955 ______________________________________________________________________________ 2) Pending vulnerabilities in SuSE Distributions and Workarounds: Clarification: In my message (Subject: "SuSE: miscellaneous"), dated Wed, 15 Nov 2000, concerning the paragraph about runtime linking problems in gs (GhostScript) , I have stated that the problem will be fixed in future versions of the SuSE distribution. This does not touch the fact that we will of course provide fixes for the older distributions. - pine The packages (version 4.30) are on our ftp server and can be downloaded. The SuSE security announcement is pending. - netscape Michal Zalewski has reported a buffer overflow in Netscape's html parser code. A specially crafted html document may cause the browser to execute arbitrary code as the user calling the netscape program. The packages are available for download on ftp.suse.com. A security announcement is on the way to address the issue. - gs (ghostscript) Two vulnerabilities have been found in the ghostscript package as shipped with SuSE distributions: Insecure temporary file handling and a linker problem that could make gs runtime-link against ./libc.so.6. We're currently working on update packages. In the meanwhile, it is advised to not run gs or applications that call gs from within a world- writeable directory. - jed The text editor jed saves files in /tmp upon emergency termination in an insecure way. This problem was fixed with the release of SuSE-6.3 after a SuSE-internal code audit by Thomas Biege . The information about the existence of this bug was not communicated to the public because the editor was not very widely used at that time. We will provide update packages for the SuSE releases 6.0, 6.1 and 6.2 shortly. ______________________________________________________________________________ 3) standard appendix: SuSE runs two security mailing lists to which any interested party may subscribe: This email address is being protected from spambots. You need JavaScript enabled to view it. - general/linux/SuSE security discussion. All SuSE security announcements are sent to this list. To subscribe, send an email to . This email address is being protected from spambots. You need JavaScript enabled to view it. - SuSE's announce-only mailing list. Only SuSE's security annoucements are sent to this list. To subscribe, send an email to . For general information or the frequently asked questions (faq) send mail to: or respectively. ============================================== SuSE's security contact is . ============================================== Regards, Roman Drahtmüller. - - -- - - | Roman Drahtmüller // "Caution: Cape does | SuSE GmbH - Security Phone: // not enable user to fly." | Nürnberg, Germany +49-911-740530 // (Batman Costume warning label) | - - ______________________________________________________________________________ The information in this advisory may be distributed or reproduced, provided that the advisory is not modified in any way. SuSE GmbH makes no warranties of any kind whatsoever with respect to the information contained in this security advisory. Type Bits/KeyID Date User ID pub 2048/3D25D3D9 1999/03/06 SuSE Security Team - -----BEGIN PGP PUBLIC KEY BLOCK----- Version:2.6.3i mQENAzbhLQQAAAEIAKAkXHe0lWRBXLpn38hMHy03F0I4Sszmoc8aaKJrhfhyMlOA BqvklPLE2f9UrI4Xc860gH79ZREwAgPt0pi6+SleNFLNcNFAuuHMLQOOsaMFatbz JR9i4m/lf6q929YROu5zB48rBAlcfTm+IBbijaEdnqpwGib45wE/Cfy6FAttBHQh 1Kp+r/jPbf1mYAvljUfHKuvbg8t2EIQz/5yGp+n5trn9pElfQO2cRBq8LFpf1l+U P7EKjFmlOq+Gs/fF98/dP3DfniSd78LQPq5vp8RL8nr/o2i7jkAQ33m4f1wOBWd+ cZovrKXYlXiR+Bf7m2hpZo+/sAzhd7LmAD0l09kABRG0JVN1U0UgU2VjdXJpdHkg VGVhbSA8c2VjdXJpdHlAc3VzZS5kZT6JARUDBRA24S1H5Fiyh7HKPEUBAVcOB/9b yHYji1/+4Xc2GhvXK0FSJN0MGgeXgW47yxDL7gmR4mNgjlIOUHZj0PEpVjWepOJ7 tQS3L9oP6cpj1Fj/XxuLbkp5VCQ61hpt54coQAvYrnT9rtWEGN+xmwejT1WmYmDJ xG+EGBXKr+XP69oIUl1E2JO3rXeklulgjqRKos4cdXKgyjWZ7CP9V9daRXDtje63 Om8gwSdU/nCvhdRIWp/Vwbf7Ia8iZr9OJ5YuQl0DBG4qmGDDrvImgPAFkYFzwlqo choXFQ9y0YVCV41DnR+GYhwl2qBd81T8aXhihEGPIgaw3g8gd8B5o6mPVgl+nJqI BkEYGBusiag2pS6qwznZiQEVAwUQNuEtBHey5gA9JdPZAQFtOAf+KVh939b0J94u v/kpg4xs1LthlhquhbHcKNoVTNspugiC3qMPyvSX4XcBr2PC0cVkS4Z9PY9iCfT+ x9WM96g39dAF+le2CCx7XISk9XXJ4ApEy5g4AuK7NYgAJd39PPbERgWnxjxir9g0 Ix30dS30bW39D+3NPU5Ho9TD/B7UDFvYT5AWHl3MGwo3a1RhTs6sfgL7yQ3U+mvq MkTExZb5mfN1FeaYKMopoI4VpzNVeGxQWIz67VjJHVyUlF20ekOz4kWVgsxkc8G2 saqZd6yv2EwqYTi8BDAduweP33KrQc4KDDommQNDOXxaKOeCoESIdM4p7Esdjq1o L0oixF12Cg==pIeS - -----END PGP PUBLIC KEY BLOCK----- -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv iQEVAwUBOh6OSney5gA9JdPZAQFsKAf/Rn7V0D4N4nRRhWcYvvtNeIYfYsitOByR 7W/Q1Mbh3WIjDehw+3enCZi9PBB5GnoMVyMRthaUH1+1zY5DT8q/bkpgvhW3pD+F pP/ksNRwJte2mZNdd/7UUu/cS8ditCIRO65JGyttqdU6VhoGLFgXiZPE0YWcfyJj VoCRR4Jv6peCodSZdfOe5DVZUTfZATdp8Fm1A5+0XAVwfgr3n/J/aoJgkRwWJ/Kr szGp7Q9TeIOzKZJOHxwKnQ+c+8ge0F2h02WsI8cq6B8HMhVwYnV4rXU4E7CmYnzm sn6lKj7qTykqajNi1zqPjGpUDNU7gH1L5zMXiiisgkacT9bavwF7lw==Uskv -----END PGP SIGNATURE----- . SuSE's alert emphasizes critical vulnerabilities in OpenSSH that pose security risks and provides vital configuration advice to minimize threats from unauthorized remote access. Openssh Vulnerabilities, SuSE Security Advisory, Remote Access Risks. . LinuxSecurity.com Team

Nov 24, 2000 SuSE