FreeBSD Security Advisory FreeBSD-SA-16:07.openssh

Fabricante: FreeBSD
Fecha: 15/01/2016
Identificador: FreeBSD-SA-16:07.openssh
FreeBSD Security Advisory FreeBSD-SA-16:07.openssh
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-16:07.openssh Security Advisory The FreeBSD Project Topic: OpenSSH client information leak Category: contrib Module: openssh Announced: 2016-01-14 Credits: Qualys Security Advisory Team Affects: All supported versions of FreeBSD. Corrected: 2016-01-14 22:42:43 UTC (stable/10, 10.2-STABLE) 2016-01-14 22:45:33 UTC (releng/10.2, 10.2-RELEASE-p10) 2016-01-14 22:47:54 UTC (releng/10.1, 10.1-RELEASE-p27) 2016-01-14 22:50:35 UTC (stable/9, 9.3-STABLE) 2016-01-14 22:53:07 UTC (releng/9.3, 9.3-RELEASE-p34) CVE Name: CVE-2016-0777 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background OpenSSH is an implementation of the SSH protocol suite, providing an encrypted and authenticated transport for a variety of services, including remote shell access. The ssh(1) is client side utility used to login to remote servers. II. Problem Description The OpenSSH client code contains experimental support for resuming SSH connections (roaming). The matching server code has never been shipped, but the client code was enabled by default and could be tricked by a malicious server into leaking client memory to the server, including private client user keys. III. Impact A user that authenticates to a malicious or compromised server may reveal private data, including the private SSH key of the user. IV. Workaround The vulnerable code in the client can be completely disabled by adding 'UseRoaming no' to the global ssh_config(5) file, or to user configuration in ~/.ssh/config, or by passing -oUseRoaming=no on the command line. All current remote ssh(1) sessions need to be restared after changing the configuration file. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. 2) To update your vulnerable system via a binary patch: Systems running a RELEASE version of FreeBSD on the i386 or amd64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install 3) To update your vulnerable system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch https://security.FreeBSD.org/patches/SA-16:07/openssh.patch # fetch https://security.FreeBSD.org/patches/SA-16:07/openssh.patch.asc # gpg --verify openssh.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile the operating system using buildworld and installworld as described in . VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/9/ r294053 releng/9.3/ r294054 stable/10/ r294049 releng/10.1/ r294051 releng/10.2/ r294052 - ------------------------------------------------------------------------- To see which files were modified by a particular revision, run the following command, replacing NNNNNN with the revision number, on a machine with Subversion installed: # svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base Or visit the following URL, replacing NNNNNN with the revision number: VII. References The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJWmH8uAAoJEO1n7NZdz2rnZ3MQAMPm2/+gM/83HbibOzRXfo7v 4D3j93BOEGltCQx8y+Stu3Y/CNA6eRYVPvD0u65DeO2bevQcYPQbfHSa5fxYgjWQ yqmLAvB+KZyGxAWZZhXsOWS6oUsK6y75jaWho3Oq19VLps8CWqHauvIyk0b1z/KA IlYYcXOdAvDgLoZHVcLbKU0jdOvMmc/iwxhx0aPVu4D2LXIr59xQcA/AsbKobk5V oqWt5CaaiZCXmVaw9eQhqNuXYC3zoY2/eh8FKG6IkIH9eyL6qQUIxumluxcui1MZ 25tZjp+OsmpVLgWxUyKKyQOVj3rRjaiRBwyUMUk+87GwmW+5b71UYjtVfQw9KHf1 KjGfylhu1oFcw5vCiul9xMm5jtBweqly1U1GEigybkDzaRNM3wheaOjWJVplU9Ku pNYZJo7cBi19KztUUyF9AUroAdVGVO4fzRtHxWUPIBxXFpgvlXijw/AMckTGcqWy TcEh45zSs2TScP1F8GeLPvmWUFbcChTCYWUIzFVUakEVeM5iRmx6B9qMFcN7YUS7 aFiraTIJFhaYrBbKK95CMfFvDAXwe+tBoGfLjXIfZdHcrmB6jkDyUue8ItopsAS0 hozJQUgcnZzzG+KcWODEB2xMdZSqldUoztDXJII3aisCf39ZXN5IFNJHti13tc8l Lw/p7lOx/U4SIq+QNqqy =EApM -----END PGP SIGNATURE-----