Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2020.0992 Kernel memory disclosure with nested jails 20 March 2020 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: jail Publisher: FreeBSD Operating System: FreeBSD UNIX variants (UNIX, Linux, OSX) Impact/Access: Reduced Security -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2020-7453 Original Bulletin: https://security.freebsd.org/advisories/FreeBSD-SA-20:08.jail.asc Comment: This advisory references vulnerabilities in products which run on platforms other than FreeBSD. It is recommended that administrators running jail check for an updated version of the software for their operating system. - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-20:08.jail Security Advisory The FreeBSD Project Topic: Kernel memory disclosure with nested jails Category: core Module: kern Announced: 2020-03-19 Credits: Hans Christian Woithe <chwoithe@yahoo.com> Affects: All supported versions of FreeBSD. Corrected: 2020-03-16 21:12:46 UTC (stable/12, 12.1-STABLE) 2020-03-19 16:51:33 UTC (releng/12.1, 12.1-RELEASE-p3) 2020-03-16 21:12:32 UTC (stable/11, 11.3-STABLE) 2020-03-19 16:51:33 UTC (releng/11.3, 11.3-RELEASE-p7) CVE Name: CVE-2020-7453 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 The jail_set(2) system call allows a system administrator to lock up a process and all its descendants inside a closed environment with very limited ability to affect the system outside that environment, even for processes with superuser privileges. The jail_get(2) system call allows a system administrator to read the configuration of running jails. II. Problem Description A missing NUL-termination check for the jail_set(2) configration option "osrelease" may return more bytes when reading the jail configuration back with jail_get(2) than were originally set. III. Impact For jails with a non-default setting of children.max > 0 ("nested jails") a superuser inside a jail can create a jail and may be able to read and take advantage of exposed kernel memory. IV. Workaround No workaround is available. Systems not altering the default settings of the jail configuration option children.max=0 are not affected as a root on the base system has access to kernel memory by other means and a super user inside a jail cannot create further jails. V. Solution Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date, and reboot. Perform one of the following: 1) 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 # shutdown -r +10min "Rebooting for a security update" 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-20:08/kern_jail.patch # fetch https://security.FreeBSD.org/patches/SA-20:08/kern_jail.patch.asc # gpg --verify kern_jail.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile your kernel as described in <URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the system. VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - - ------------------------------------------------------------------------- stable/12/ r359021 releng/12.1/ r359142 stable/11/ r359020 releng/11.3/ r359142 - - ------------------------------------------------------------------------- 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 <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-7453> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-20:08.jail.asc> - -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAl5zplhfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cKWdw//ZFfaoCenbVtvB6a4JW9HOT0yMoDXup+OdpjbhUTsJSyvDB9eZUSiZJ7u 4rQZpYQZotND2I/U8BSUjcJlDVzhTn6WN1yZFpWI9oFrSJhKxkwGMuetocUw7MgE ++WaaVueodMBjG7+v7mUmr5pXomdpxCO4XZxTW0BCm3Pvydera1kZVHzQ2pAw0On cnOiSN+v04latfkjjdjPv+oC8GUsI3Q+4jF745MN9dND+4KV/4CW5BJg6sUiJakx WB6cXayxp+Q/WPoB4OS/w3loe1FGIqESjXMxdHAV0n9eVofv8+h0rQt5kQ9oFpCm Ql2NUG7xKqoidGlhzff5w0j5+VNXA/exv+sH/lQTZO5xJa/5Ti1wlUxsrp/8jO9Z vRDd3CwjOIG+dFBSAXWcAaSedJ+Ax97RVbfKmYiy5B7ujJp/X6rJXU2G3zOhObCS 8/E+KHlj9YT4hN73zDeGiw5zKVjbfVQp661mKgP1lO+4Mv9357F8epux+CV3fdb6 BBttCm8l8ubhfr12fmBAfXUXDx7stNTpvcgphGUB0v6Sfxbv0OHoGzfAGrQ3i3LP Os7OoFRJ+2SJ/G8xpjVjriOsAoLeUX43JIlPTOEvU2mhol/M717Rwn94ndqXfNJh XCF2AaOVXxBpdx2Vik3FBTGZvAfTCxMQOZwGn7zVzpbxlCbasKM= =13XM - -----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: https://www.auscert.org.au/bulletins/ =========================================================================== 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). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBXnQULmaOgq3Tt24GAQj7YBAAjg0/qyvwXWLiXpvEdatk7yFdPZah3Fwl o7eH2ukkI1ifSQN2/zW41Jb5kYNgkOehvp5hNG7WQSUeSKZmmxU4xLcTpTcMZ78O AS1q4/nBTpSDNAvR3vdFMAbe+fLYqg4dNWlZlZIGiaYyVuS4qKiPNlLdO4d9i1w6 XYXThz0kW6FKRIH4unbH6PCi0REbc8RWE7CmtwB+C7Pg9RVySPXugqsr7SxnBdlO yGSsrE+0k/Fcqh/N7dzHd3d9ejgvGIKeFpga+0X6s7+BNFGFb7DnMs9V0uQCn6+p SOtGvuE2sfrjMX36AREyqcARiM+syfmScN9gnCPjrlqUi8taczkEiu1/J3mEitje fJdKoEKhAIwDqZvVQiYW5Dli9AeFQSj05blCqbWAEBhIpajpfsckIrLkmSD41VCW r05OMdo26N4AkScEnPi/e8mN3uqEWsW+wimgRoDvcexLqiWgc5D2s/2jKM9AW0E+ o7XKiiM62dz1uX5DZc8MvbeuYG1ql7l7YPzTcuGqsw/6ZtBjMZQnarCPAxtuF5U/ o+qhuKEEEvVEE2HqIloq1W+x9Z5xjKZNx95RdY3fsYGsMdbOS3tQm4jtT7Kk9rgc 6TQ4Qc3BbmVoEOrWLlxhj015b3YY1FVjs+kz0Wbj+sjt86RInPpoU82cf13r7aUq WbTo1alOjLY= =WV7q -----END PGP SIGNATURE-----