1. Forum
  2. Usenet
  3. COMP.UNIX.BSD.FREEBSD.ANN

  • [FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-18:04.vt

    From FreeBSD Security Advisories@21:1/5 to All on Wed Apr 4 07:00:00 2018
    -----BEGIN PGP SIGNED MESSAGE-----
    Hash: SHA512

    ============================================================================= FreeBSD-SA-18:04.vt Security Advisory
    The FreeBSD Project

    Topic: vt console memory disclosure

    Category: core
    Module: vt console
    Announced: 2018-04-04
    Credits: Dr Silvio Cesare of InfoSect
    Affects: All supported versions of FreeBSD.
    Corrected: 2018-04-04 05:24:59 UTC (stable/11, 11.1-STABLE)
    2018-04-04 05:33:56 UTC (releng/11.1, 11.1-RELEASE-p9)
    2018-04-04 05:26:33 UTC (stable/10, 10.4-STABLE)
    2018-04-04 05:33:56 UTC (releng/10.4, 10.4-RELEASE-p8)
    2018-04-04 05:33:56 UTC (releng/10.3, 10.3-RELEASE-p29)
    CVE Name: CVE-2018-6917

    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

    On FreeBSD 11 and later, and FreeBSD 10.x systems that boot via UEFI, the default system video console is provided by the vt(4) driver. The console allows the user, including an unprivileged user, to load a font at runtime.

    II. Problem Description

    Insufficient validation of user-provided font parameters can result in an integer overflow, leading to the use of arbitrary kernel memory as glyph
    data. Characters that reference this data can be displayed on the screen, effectively disclosing kernel memory.

    III. Impact

    Unprivileged users may be able to access privileged kernel data.

    Such memory might contain sensitive information, such as portions of the file cache or terminal buffers. This information might be directly useful, or it might be leveraged to obtain elevated privileges in some way; for example,
    a terminal buffer might include a user-entered password.

    IV. Workaround

    The syscons sc(4) system console is not affected by this issue and may be
    used on systems that do not boot via UEFI. To use the syscons console,
    set the kern.vty tunable in /boot/loader.conf as described in sc(4), and reboot. No workaround is available for systems that boot via UEFI.

    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

    A reboot is required after the upgrade.

    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-18:04/vt.patch
    # fetch https://security.FreeBSD.org/patches/SA-18:04/vt.patch.asc
    # gpg --verify vt.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/10/ r331983 releng/10.3/ r331984 releng/10.4/ r331984 stable/11/ r331982 releng/11.1/ r331984
    - -------------------------------------------------------------------------

    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-2018-6917>

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-18:04.vt.asc> -----BEGIN PGP SIGNATURE-----

    iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAlrEZttfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cI5CBAAmZS+2l3qNafZ0FQDKONeX+jiyJt6lPWk2LUd/jJXnEnVjqiP/pW1YpC0 9oob5gFaCt8YEpQRIPGU1VwIfX16KeMSiM2TYnZXAaTzSo5ecWemrQ706ds7hy+m FmlyoqoqmDn3AyziTeJAxFc2QVZ5jo25KWZL7zMJdNjGqzFao4UktY01Sy9fB3Ak rgi/AInZV1FGt1KrH04zJpK+WSfNtM553e7KfFlmD6cR+yXViHfGHl6TBYcb1H3y 8wjfZmdlfyFMB84bQ5bw9iqx5fHhth4s/0sbAErRAS/PeWOKF9uxSVy3t4p160BZ Ym7k4PXYO8hUH9n5mqDzg/asPkRA8nJMqmUtvBJrdUMi9VhQqOybhddZNAZp7RGb 6BtlsBUaRRmxA9tm4h5nbk+Fy9/qqtkcOdsJNqqAdSk4nTTkkkKPNPrIkXKcW4HE qv8c71xDkpbAGfQjkC2B4VXg9uoQIi36F8843ha6UbhdL2urSWWPXLBOoSupRAyp PkB35tvulXyJ/cRRf/FfAL+lSmoqImi2WjSjpd+fqABWSaxrypJqI0Cca3ySdhVG mylVk2sDW/d27Wltyd1Pdy9qXHVSEoKwdWemCamAABFwaCf49D1xrgysCrdY+uFp zydy8rxJ0Bht18n4Yhp+WveujRFwamvGjWxYbxJ0g+LD+SWD7Zs=
    =L6/K
    -----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)