158 lines
6.1 KiB
Text
158 lines
6.1 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-SA-17:01.openssh Security Advisory
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The FreeBSD Project
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Topic: OpenSSH multiple vulnerabilities
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Category: contrib
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Module: OpenSSH
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Announced: 2017-01-11
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Affects: All supported versions of FreeBSD.
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Corrected: 2017-01-11 05:56:40 UTC (stable/11, 11.0-STABLE)
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2017-01-11 06:01:23 UTC (releng/11.0, 11.0-RELEASE-p7)
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2017-01-11 05:56:40 UTC (stable/10, 10.3-STABLE)
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2017-01-11 06:01:23 UTC (releng/10.3, 10.3-RELEASE-p16)
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CVE Name: CVE-2016-10009, CVE-2016-10010
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For general information regarding FreeBSD Security Advisories,
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including descriptions of the fields above, security branches, and the
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following sections, please visit <URL:https://security.FreeBSD.org/>.
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I. Background
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OpenSSH is an implementation of the SSH protocol suite, providing an
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encrypted and authenticated transport for a variety of services,
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including remote shell access.
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OpenSSH supports accessing keys provided by a PKCS#11 token.
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II. Problem Description
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The ssh-agent(1) agent supports loading a PKCS#11 module from outside a
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trusted whitelist. An attacker can request loading of a PKCS#11 module
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across forwarded agent-socket. [CVE-2016-10009]
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When privilege separation is disabled, forwarded Unix domain sockets
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would be created by sshd(8) with the privileges of 'root' instead of
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the authenticated user. [CVE-2016-10010]
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III. Impact
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A remote attacker who have control of a forwarded agent-socket on a
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remote system and have the ability to write files on the system
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running ssh-agent(1) agent can run arbitrary code under the same user
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credential. Because the attacker must already have some control on
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both systems, it is relatively hard to exploit this vulnerability in
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a practical attack. [CVE-2016-10009]
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When privilege separation is disabled (on FreeBSD, privilege separation
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is enabled by default and has to be explicitly disabled), an authenticated
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attacker can potentially gain root privileges on systems running OpenSSH
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server. [CVE-2016-10010]
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IV. Workaround
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Systems not running ssh-agent(1) and sshd(8) services are not affected.
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System administrators may remove ssh-agent(1) to mitigate CVE-2016-10009.
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System administrators should enable privilege separation when running
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OpenSSH server, which is the FreeBSD default, to mitigate CVE-2016-10010.
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V. Solution
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Perform one of the following:
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1) Upgrade your vulnerable system to a supported FreeBSD stable or
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release / security branch (releng) dated after the correction date.
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Kill all running ssh-agent(1) process and restart sshd(8) service.
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A reboot is recommended but not required.
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2) To update your vulnerable system via a binary patch:
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Systems running a RELEASE version of FreeBSD on the i386 or amd64
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platforms can be updated via the freebsd-update(8) utility:
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# freebsd-update fetch
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# freebsd-update install
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Kill all running ssh-agent(1) process and restart sshd(8) service.
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A reboot is recommended but not required.
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3) To update your vulnerable system via a source code patch:
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The following patches have been verified to apply to the applicable
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FreeBSD release branches.
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a) Download the relevant patch from the location below, and verify the
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detached PGP signature using your PGP utility.
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# fetch https://security.FreeBSD.org/patches/SA-17:01/openssh.patch
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# fetch https://security.FreeBSD.org/patches/SA-17:01/openssh.patch.asc
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# gpg --verify openssh.patch.asc
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b) Apply the patch. Execute the following commands as root:
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# cd /usr/src
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# patch < /path/to/patch
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c) Recompile the operating system using buildworld and installworld as
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described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.
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Kill all running ssh-agent(1) process and restart sshd(8) service.
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A reboot is recommended but not required.
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VI. Correction details
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The following list contains the correction revision numbers for each
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affected branch.
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Branch/path Revision
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- -------------------------------------------------------------------------
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stable/10/ r311915
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releng/10.3/ r311916
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stable/11/ r311915
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releng/11.0/ r311916
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- -------------------------------------------------------------------------
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To see which files were modified by a particular revision, run the
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following command, replacing NNNNNN with the revision number, on a
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machine with Subversion installed:
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# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
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Or visit the following URL, replacing NNNNNN with the revision number:
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<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
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VII. References
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<URL:https://www.openssh.com/txt/release-7.4>
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<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-10009>
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<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-10010>
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The latest revision of this advisory is available at
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<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-17:01.openssh.asc>
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