• [FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-18:12.elf

    From FreeBSD Security Advisories@21:1/5 to All on Wed Sep 12 06:00:00 2018
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    ============================================================================= FreeBSD-SA-18:12.elf Security Advisory
    The FreeBSD Project

    Topic: Improper ELF header parsing

    Category: core
    Module: kernel
    Announced: 2018-09-12
    Credits: Thomas Barabosch, Fraunhofer FKIE; Mark Johnston
    Affects: All supported versions of FreeBSD.
    Corrected: 2018-09-12 05:02:11 UTC (stable/11, 11.1-STABLE)
    2018-09-12 05:07:35 UTC (releng/11.2, 11.2-RELEASE-p3)
    2018-09-12 05:07:35 UTC (releng/11.1, 11.1-RELEASE-p14)
    2018-09-12 05:03:30 UTC (stable/10, 10.4-STABLE)
    2018-09-12 05:07:35 UTC (releng/10.4, 10.4-RELEASE-p12)
    CVE Name: CVE-2018-6924

    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

    To execute a binary the kernel must parse the ELF header to determine the
    entry point address, the program interpreter, and other parameters.

    II. Problem Description

    Insufficient validation was performed in the ELF header parser, and malformed or otherwise invalid ELF binaries were not rejected as they should be.

    III. Impact

    Execution of a malicious ELF binary may result in a kernel crash or may disclose kernel memory.

    IV. Workaround

    No workaround is available.

    V. Solution

    Upgrade your vulnerable system to a supported FreeBSD stable or
    release / security branch (releng) dated after the correction date, and
    reboot.

    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 +30 "Rebooting for 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-18:12/elf.patch
    # fetch https://security.FreeBSD.org/patches/SA-18:12/elf.patch.asc
    # gpg --verify elf.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/ r338605 releng/10.4/ r338606 stable/11/ r338604 releng/11.1/ r338606 releng/11.2/ r338606
    - -------------------------------------------------------------------------

    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-2018-6924>

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-18:12.elf.asc> -----BEGIN PGP SIGNATURE-----

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