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SuSE: 2001:045 moderate: openssh local escalation threat

This is a re-release of the SuSE Security Announcement SuSE-SA:2001:044, adding another bugfix for the openssh package as well as more detailed information about the vulnerabilities to prevent misunderstandings.. ______________________________________________________________________________ SuSE Security Announcement Package: openssh Announcement-ID: SuSE-SA:2001:045 Date: Thursday, Dec 6th 2001 21:30 MET Affected SuSE versions: 6.4, 7.0, 7.1, 7.2, 7.3 Vulnerability Type: local privilege escalation Severity (1-10): 5 SuSE default package: yes Other affected systems: systems running openssh 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) Re-release of SuSE Security Announcement SuSE-SA:2001:044, brief history, Clarification, new problem fixed, upgrade information. This is a re-release of the SuSE Security Announcement SuSE-SA:2001:044, adding another bugfix for the openssh package as well as more detailed information about the vulnerabilities to prevent misunderstandings. The currently supported SuSE distributions 6.4 and newer come with two implementations of the secure shell protocol: The package names are "ssh" and "openssh". Brief history: In 1998, a vulnerability of the secure shell protocol in version 1 has been discovered and named "crc32 compensation attack". The vulnerability allows an attacker to insert arbitrary sequences into the ssh-1 protocol layer. At that time, an added patch fixed the problem in the ssh implementation (visible in the client-side verbose output of the ssh command (-v):"Installing crc compensation attack detector."). In early 2001, Michal Zalewski discovered that the widely used patch was defective and opened another security hole which is being actively exploited today. SuSE Security announcement SuSE-SA:2001:004, published February 16th 2001, available at *[1], addresses this defective patch, among other issues. Clarification/Apology: Our last openssh security announcement SuSE-SA:2001:044 (*[3]) may falsely lead to assume that the openssh-2.9.9p2 update packages on our ftp server fix the vulnerabilities known as crc32 compensation attack. This is incorrect since the openssh-2.3.0 packages released with SuSE Security announcement SuSE-SA:2000:047 in November 2000, available at *[2], already fixed the mentioned (among other) problems. The release of the openssh-2.9.9p2 update packages obsoletes the openssh-2.3.0 update packages. We explicitly regret the used wording and apologize to the openssh development team, in particular Markus Friedl and Theo De Raadt, and thank them for their excellent work on the project. Scanning utilities that can be found on the internet connect to port 22 of a server and read the version string. It should be noted that the bare knowlege of the secure shell protocol version string does not allow to determine whether a running secure shell daemon is actually vulnerable to the defective fix for the crc32 compensation attack. SuSE security receive dozens of requests about statements if the daemons in use are vulnerable or not. Please see reference *[1]. New problem fixed: This re-release of SuSE Security Announcement SuSE-SA:2001:044 (please see reference *[3] below) adds another patch to the openssh-2.9.9p2 packages: A bug allows a local attacker on the server to specify environment variables that can influence the login process if the "UseLogin" configuration option on the server side is set to "yes". If exploited, thelocal attacker on the secure shell server can execute arbitrary commands as root. In the default configuration of the package, the UseLogin option is set to "no", which means that the administrator of the server must have set the option to "yes" manually before the bug can be exploited. Users who upgraded their SuSE openssh package before December 6th 2001 should upgrade their package again. Use the command "rpm -q openssh" to see which version/release of the package you have installed, and compare this version with the one as listed below. Upgrade information: You can find out which implementation of the ssh protocol you are using with the command "rpm -qf /usr/bin/ssh". If you use the ssh-1.2.* package, please read Reference *[1]. If you use the openssh-* package, please download the rpm package for your distribution from the URL list below, verify its integrity using the methods as described in section 3) of this security announcement and install the package using the command rpm -Uhv file.rpm where file.rpm is the filename of the package that you have downloaded. References: *[1]: SUSE – Open-Source-Lösungen für Enterprise Server und Cloud | SUSE *[2]: SUSE – Open-Source-Lösungen für Enterprise Server und Cloud | SUSE *[3]: SUSE – Open-Source-Lösungen für Enterprise Server und Cloud | SUSE SPECIAL INSTALL INSTRUCTIONS: The sshd secure shell daemon on the server side has to be restarted for the new package to become active. If you are logged on on the console, the simple command "rcsshd restart" should do this for you. If you are logged on via secure shell, you should make sure that you do not terminate the connections that are established through the running secure shell daemon/its children. In this case, kill the daemon after package installation using the command kill -TERM `cat /var/run/sshd.pid` and then restart the daemon with the command /usr/sbin/sshd as root. Then, verify that the login procedure works as before. One of the main changes in the new openssh package is that the file $HOME/.ssh/authorized_keys2 is only read by the server if the file $HOME/.ssh/authorized_keys does not exist and if protocol version 2 is being used. The file $HOME/.ssh/authorized_keys2 can be removed after its contents have been added to $HOME/.ssh/authorized_keys. The two configuration files /etc/ssh/sshd_config (server side) and /etc/ssh/ssh_config (client side) contained in the openssh package do not get overwritten upon installation or upgrade, if you have changed them manually. Instead, the new configuration files are written with a .rpmnew suffix. The defaults as provided in the SuSE package make an effort to establish both convenience as well as security. NOTE: Packages for SuSE Linux distributions 7.0 and older containing cryptographic software are located on our German ftp server ftp.suse.de for legal reasons. Packages for all other distributions (7.1 and newer) can be found at their regular path at ftp.suse.com. i386 Intel Platform: SuSE-7.3 f3d60cce6d62dbf79c36a849811c19d7 source rpm: 4246e40b1e5a7b4456f2bb4c05177126 SuSE-7.2 3764a15b17b0823c6fa2e8e4aee5af69 source rpm: e9cccadf767cb80e3c588266d6886153 SuSE-7.1 4dbcdb2a544cadd36749baea890bc38e source rpm: 04400597a1b9526bc78344e8e523fa40 SuSE-7.0 29dcc882bf30cbe88c94b07bb84e7216 source rpm: b852431e4711d7f45a8bd180532325b0 SuSE-6.4 8cfe1e9d2dd964851acb42e1e13311b9 source rpm: a3686e39258d03c99fc2ba3573325c2a Sparc Platform: SuSE-7.3 32d3a1c735d2c27cb580fedeeed3a135 source rpm: 82540b2297b2d03d45118b3c23a72bf8 SuSE-7.1 The update packages for the SuSE Linux 7.1 Sparc distributions are not availableyet. The package can soon be found at SuSE-7.0 638891762f09e01b83e9c39c184ce9ea source rpm: ad3520ad8907c585f84facb742fc03bf AXP Alpha Platform: SuSE-7.1 04e815054c9bc3a1b0a1ddda8c6e2d10 source rpm: 32c39e29517fc8269f252f7cc6f18bce The update packages for the SuSE Linux AXP/Alpha distributions before SuSE-7.1 are not available on our ftp server yet. These packages can be found at the usual location in the update paths on ftp.suse.de. PPC Power PC Platform: SuSE-7.3 4b056c828675898bf482e9ecb4f91a0b source rpm: e10ed49e7319c244caf324a64f16c738 SuSE-7.1 163126a80ff0167b34c041348ef5c3c4 source rpm: 948862c53dc62e921b03766c986a4de2 SuSE-7.0 aff3785ac9670daa0e06445ad9b5a2b9 source rpm: ccfb132470cb61b52688fc12f1352b12 SuSE-6.4 ae20b7379474735126636aed05f6eeee source rpm: 2351d7667c02a1ad33e21bd39196cf0a ______________________________________________________________________________ 2) Pending vulnerabilities in SuSE Distributions and Workarounds: - We are currently testing kernel update packages for the recently found local security flaw in the ELF binary loader in the Linux kernel of all v2.4 versions and expect to be able to announce these update rpm packages soon with a re-release of our kernel security announcement. ______________________________________________________________________________ 3) standard appendix: authenticity verification, additional information - Package authenticity verification: SuSE update packages are available on many mirror ftp servers all over the world. While this service is being considered valuable and important to the free and open source software community, many users wish to be sure about the origin of the package and its content before installing the package. There are two verification methodsthat can be used independently from each other to prove the authenticity of a downloaded file or rpm package: 1) md5sums as provided in the (cryptographically signed) announcement. 2) using the internal gpg signatures of the rpm package. 1) execute the command md5sum after you downloaded the file from a SuSE ftp server or its mirrors. Then, compare the resulting md5sum with the one that is listed in the announcement. Since the announcement containing the checksums is cryptographically signed (usually using the key This email address is being protected from spambots. You need JavaScript enabled to view it. ), the checksums show proof of the authenticity of the package. We disrecommend to subscribe to security lists which cause the email message containing the announcement to be modified so that the signature does not match after transport through the mailing list software. Downsides: You must be able to verify the authenticity of the announcement in the first place. If RPM packages are being rebuilt and a new version of a package is published on the ftp server, all md5 sums for the files are useless. 2) rpm package signatures provide an easy way to verify the authenticity of an rpm package. Use the command rpm -v --checksig to verify the signature of the package, where is the filename of the rpm package that you have downloaded. Of course, package authenticity verification can only target an uninstalled rpm package file. Prerequisites: a) gpg is installed b) The package is signed using a certain key. The public part of this key must be installed by the gpg program in the directory ~/.gnupg/ under the user's home directory who performs the signature verification (usually root). You can import the key that is used by SuSE in rpm packages for SuSE Linux by saving this announcement to a file ("announcement.txt") and running thecommand (do "su -" to be root): gpg --batch; gpg < announcement.txt | gpg --import SuSE Linux distributions version 7.1 and thereafter install the key " This email address is being protected from spambots. You need JavaScript enabled to view it. " upon installation or upgrade, provided that the package gpg is installed. The file containing the public key is placed at the toplevel directory of the first CD (pubring.gpg) and at . - 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 or . The public key is listed below. ====================================================================______________________________________________________________________________ The information in this advisory may be distributed or reproduced, provided that the advisory is not modified in any way. In particular, it is desired that the cleartext signature shows proof of the authenticity of the text. SuSE GmbH makes no warranties of any kind whatsoever with respect to the information contained in this security advisory. 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Ubuntu Security Notice: openssl announces urgent patch for critical bugs linked to privilege escalation risks. Essential upgrade information provided.. OpenSSH Security Fix, Local Escalation Threat, SuSE Bugfix Announcement, Secure Shell Issues. . LinuxSecurity.com Team

Dec 06, 2001 SuSE