-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
============================================================================= FreeBSD-SA-20:28.bhyve_vmcs Security Advisory
The FreeBSD Project
Topic: bhyve privilege escalation via VMCS access
Category: core
Module: bhyve
Announced: 2020-09-15
Credits: Patrick Mooney
Affects: All supported versions of FreeBSD.
Corrected: 2020-09-15 21:28:47 UTC (stable/12, 12.2-STABLE)
2020-09-15 21:43:41 UTC (releng/12.2, 12.2-BETA1-p1)
2020-09-15 21:43:41 UTC (releng/12.1, 12.1-RELEASE-p10)
2020-09-15 21:28:47 UTC (stable/11, 11.4-STABLE)
2020-09-15 21:43:41 UTC (releng/11.4, 11.4-RELEASE-p4)
2020-09-15 21:43:41 UTC (releng/11.3, 11.3-RELEASE-p14)
CVE Name: CVE-2020-24718
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(8) is a hypervisor that supports running a variety of guest operating systems in virtual machines on AMD and Intel CPUs.
II. Problem Description
AMD and Intel CPUs support hardware virtualization using specialized data structures that control various aspects of guest operation. These are the Virtual Machine Control Structure (VMCS) on Intel CPUs, and the Virtual
Machine Control Block (VMCB) on AMD CPUs. Insufficient access controls allow root users, including those running in a jail, to change these data
structures.
III. Impact
An attacker with host root access (including to a jailed bhyve instance) can use this vulnerability to achieve kernel code execution.
IV. Workaround
No workaround is available. This issue is likely of concern only to systems relying on running bhyve in jail(8) for security domain separation.
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-20:28/bhyve_vmcs.patch
# fetch
https://security.FreeBSD.org/patches/SA-20:28/bhyve_vmcs.patch.asc
# gpg --verify bhyve_vmcs.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/ r365777 releng/12.2/ r365779 releng/12.1/ r365779 stable/11/ r365777 releng/11.4/ r365779 releng/11.3/ r365779
- -------------------------------------------------------------------------
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-2020-24718>
The latest revision of this advisory is available at <URL:
https://security.FreeBSD.org/advisories/FreeBSD-SA-20:28.bhyve_vmcs.asc> -----BEGIN PGP SIGNATURE-----
iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAl9hOJdfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cKJBQ//UOwIgcc2n+Yr0MrNIs2XzLjmKBsuVfIrFni0GGJFFSAUd7Kzw7oeY4ng e9JURtfV6NlU63QkaRw+QqgvnXm5vLbgO+oWuedsj33eNgUNdUinZinieZuFAyAt BBgfMJ3D9X7HffIw1iKN/DWaealFJ1SHtKYzVssTBx/7ju+SFj5HkwLh/7QzKBYO CoeNE7RN2kSDmvvEKMdN17QyM4+H3wYpsnylWHa89slIe1xj0eVqgnGw2NrjjKlV N2DAQM+MvdJ+W8oA0idEvBZj55uHV9OlgIwJCDi0/u5yHPJkhuYYuHsf0oyW+NT6 gWvzwTI27IAAyYKK57pGVP7x4sy8VhsDItzqubhDqa/zjNZM9SYOtLYiOnDjev2B nqC2mV08XpC9lfwd3EDPGv+FYbTTe9OzirlJBnbMnwhj/p0sPMYCtuWKp/MyQyyD 1yhUJJlZgI6HdrTOOeqhObNDtEz75MI1bpLVmjq9VMLz1PtzdNFDcNmyvtTOpMut vZDFgCqtkpcukqxfqV1EJAWr0UWnaUyPc0klbmLwrQCpTWDOBT7QK+S5ZtNLQqu4 c6UJ7CQLNPn9nEjf16D8dZ1Iy3AJyPmtv7ehEkKFjJtNIwitCx/AIzKiXXzzxe56 boJoQL0pmgJkv3tjP5dEMeSx5SA4mrhtKCL+ri3/ZFXHxtcDNsQ=
=Jluz
-----END PGP SIGNATURE-----
_______________________________________________
freebsd-announce@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-announce
To unsubscribe, send any mail to "
freebsd-announce-unsubscribe@freebsd.org"
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)