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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2016.2492 bhyve - privilege escalation vulnerability 26 October 2016 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: bhyve Publisher: FreeBSD Operating System: FreeBSD Impact/Access: Root Compromise -- Existing Account Resolution: Patch/Upgrade Original Bulletin: https://security.freebsd.org/advisories/FreeBSD-SA-16:32.bhyve.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-16:32.bhyve Security Advisory The FreeBSD Project Topic: bhyve - privilege escalation vulnerability Category: core Module: bhyve Announced: 2016-10-25 Credits: Ilja van Sprundel, IOActive Affects: FreeBSD 11.0 amd64 Corrected: 2016-10-25 17:15:32 UTC (stable/11, 11.0-STABLE) 2016-10-25 17:11:20 UTC (releng/11.0, 11.0-RELEASE-p2) For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:https://security.FreeBSD.org/>. I. Background bhyve is a BSD licensed hypervisor that supports running a variety of virtual machines (guests). II. Problem Description An unchecked array reference in the VGA device emulation code could potentially allow guests access to the heap of the bhyve process. Since the bhyve process is running as root, this may allow guests to obtain full control of the hosts they are running on. III. Impact For bhyve virtual machines with the "fbuf" framebuffer device configured, if exploited, a malicious guest could obtain full access to not just the host system, but to other virtual machines running on the system. IV. Workaround No workaround is available, however systems not using bhyve for virtualization are not vulnerable. Additionally systems using bhyve but without the "fbuf" framebuffer device configured are not vulnerable. V. Solution Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. No reboot is needed. Rather the bhyve process for vulnerable virtual machines should be restarted. Perform one of the following: 1) To update your vulnerable system via a binary patch: Systems running a RELEASE version of FreeBSD on the amd64 platforms can be updated via the freebsd-update(8) utility. 2) 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-16:32/bhyve.patch # fetch https://security.FreeBSD.org/patches/SA-16:32/bhyve.patch.asc # gpg --verify bhyve.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch Recompile the operating system using buildworld and installworld as described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>. Restart the bhyve process(es). VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - - ------------------------------------------------------------------------- stable/11/ r307939 releng/11.0/ r307935 - - ------------------------------------------------------------------------- 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: <URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-16:32.bhyve.asc> - -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJYD5UbAAoJEO1n7NZdz2rnOAcP/03LJPbzVE05gIkN+j8z4jz5 Q/EX+zGgid5omIqslsiM6obDNupnH3HYE7Suv5sCJky9pyX8mv1g3jTkxXzm+32k 9rCcBtGdIviKKG8GNuMa56ZU5EvgUkwndn4qTi7KmZ/+1l8UGRCAsU04L6qQHwb2 Si7WcgZLse+epkYAgzyje+YFR/Ib2xc3vdXXpj+uxlQWs6U3RZ95v+6M5ARhBHes YJ34QKphy/PaT02hI9AvLU6aB4hkN5XVE2uHgpciNRLp0DF3XwqHRYbDx2bACifS ge7hbpsSCZuOayYWdtw8gcbzJXxX1fMv1q9ntj5XLh/a4av7coHWYPHDYmIC7Inb RNAhynR8W9SWFZ1EqUEWhKeWPwpKgiy1e4+CpDm5wbnj+CzJLc08tMU77jIUV6In ilJkZ04sv25mjOdnjSkjt6PnXmT1n+UrWdKjOYsAkaWiHpAUzGT2dSgRfn8zh5wv hc1368Z2v2v43HJ+Y4x0M0VVuuEydEHB+sWBhn8evxlQ6KIAC2sdi7juP4TLAgkj A1kA3Oob4+pGlxzTGgHDE+/HzHnGEfmoWHS/u0dmDiUuTlQDKQCdCEUnjfRdJYuc 3fbigdY70d2wx6igs4VZszSQLu4c4ranewy3ORS1OghpOjnvO7mvJVUbseusLaNC fYkumZ2XfUaJuya63z7z =gyCa - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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