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Posted on 12 April 2017
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FreeBSD-SA-17:03.ntp Security Advisory
The FreeBSD Project
Topic: Multiple vulnerabilities of ntp
Category: contrib
Module: ntp
Announced: 2017-04-12
Credits: Network Time Foundation
Affects: All supported versions of FreeBSD.
Corrected: 2017-03-28 04:48:17 UTC (stable/11, 11.0-STABLE)
2017-04-12 06:24:35 UTC (releng/11.0, 11.0-RELEASE-p9)
2017-03-28 04:48:55 UTC (stable/10, 10.3-STABLE)
2017-04-12 06:24:35 UTC (releng/10.3, 10.3-RELEASE-p18)
CVE Name: CVE-2017-6464, CVE-2017-6462, CVE-2017-6463, CVE-2016-9042
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 ntpd(8) daemon is an implementation of the Network Time Protocol (NTP)
used to synchronize the time of a computer system to a reference time
source.
II. Problem Description
A vulnerability was discovered in the NTP server's parsing of configuration
directives. [CVE-2017-6464]
A vulnerability was found in NTP, in the parsing of packets from the
DPTS Clock. [CVE-2017-6462]
A vulnerability was discovered in the NTP server's parsing of configuration
directives. [CVE-2017-6463]
A vulnerability was found in NTP, affecting the origin timestamp check
function. [CVE-2016-9042]
III. Impact
A remote, authenticated attacker could cause ntpd to crash by sending a
crafted message. [CVE-2017-6463, CVE-2017-6464]
A malicious device could send crafted messages, causing ntpd to crash.
[CVE-2017-6462]
An attacker able to spoof messages from all of the configured peers
could send crafted packets to ntpd, causing later replies from those
peers to be discarded, resulting in denial of service. [CVE-2016-9042]
IV. Workaround
No workaround is available, but systems not running ntpd(8) are not
affected. Network administrators are advised to implement BCP-38,
which helps to reduce the risk associated with these attacks.
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.
The ntpd service has to be restarted after the update. A reboot is
recommended but not required.
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
The ntpd service has to be restarted after the update. A reboot is
recommended but not required.
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.
[FreeBSD 11.0]
# fetch https://security.FreeBSD.org/patches/SA-17:03/ntp-11.0.patch.xz
# fetch https://security.FreeBSD.org/patches/SA-17:03/ntp-11.0.patch.xz.asc
# gpg --verify ntp-11.0.patch.xz.asc
[FreeBSD 10.3]
# fetch https://security.FreeBSD.org/patches/SA-17:03/ntp-10.3.patch.xz
# fetch https://security.FreeBSD.org/patches/SA-17:03/ntp-10.3.patch.xz.asc
# gpg --verify ntp-10.3.patch.xz.asc
b) Apply the patch. Execute the following commands as root:
# cd /usr/src
# patch < /path/to/patch
c) Recompile the operating system using buildworld and installworld as
described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.
Restart the applicable daemons, or reboot the system.
VI. Correction details
The following list contains the correction revision numbers for each
affected branch.
Branch/path Revision
- -------------------------------------------------------------------------
stable/10/ r316069
releng/10.3/ r316722
stable/11/ r316068
releng/11.0/ r316722
- -------------------------------------------------------------------------
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-2016-9042>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-6462>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-6463>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-6464>
The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-17:03.ntp.asc>
