-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-14:02.ntpd Security Advisory The FreeBSD Project Topic: ntpd distributed reflection Denial of Service vulnerability Category: contrib Module: ntpd Announced: 2014-01-14 Affects: All supported versions of FreeBSD. Corrected: 2014-01-14 19:04:33 UTC (stable/10, 10.0-PRERELEASE) 2014-01-14 19:12:40 UTC (releng/10.0, 10.0-RELEASE) 2014-01-14 19:12:40 UTC (releng/10.0, 10.0-RC5-p1) 2014-01-14 19:12:40 UTC (releng/10.0, 10.0-RC4-p1) 2014-01-14 19:12:40 UTC (releng/10.0, 10.0-RC3-p1) 2014-01-14 19:12:40 UTC (releng/10.0, 10.0-RC2-p1) 2014-01-14 19:12:40 UTC (releng/10.0, 10.0-RC1-p1) 2014-01-14 19:20:41 UTC (stable/9, 9.2-STABLE) 2014-01-14 19:42:28 UTC (releng/9.2, 9.2-RELEASE-p3) 2014-01-14 19:42:28 UTC (releng/9.1, 9.1-RELEASE-p10) 2014-01-14 19:20:41 UTC (stable/8, 8.4-STABLE) 2014-01-14 19:42:28 UTC (releng/8.4, 8.4-RELEASE-p7) 2014-01-14 19:42:28 UTC (releng/8.3, 8.3-RELEASE-p14) CVE Name: CVE-2013-5211 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://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 The ntpd(8) daemon supports a query 'monlist' which provides a history of recent NTP clients without any authentication. III. Impact An attacker can send 'monlist' queries and use that as an amplification of a reflection attack. IV. Workaround The administrator can implement one of the following possible workarounds to mitigate the attack: 1) Restrict access to ntpd(8). This can be done by adding the following lines to /etc/ntp.conf: restrict -4 default nomodify nopeer noquery notrap restrict -6 default nomodify nopeer noquery notrap restrict 127.0.0.1 restrict -6 ::1 restrict 127.127.1.0 And restart the ntpd(8) daemon. Time service is not affected and the administrator can still perform queries from local host. 2) Use IP based restrictions in ntpd(8) itself or in IP firewalls to restrict which systems can access ntpd(8). 3) Replace the base system ntpd(8) with net/ntp-devel (version 4.2.7p76 or newer) 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 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 http://security.FreeBSD.org/patches/SA-14:02/ntpd.patch # fetch http://security.FreeBSD.org/patches/SA-14:02/ntpd.patch.asc # gpg --verify ntpd.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch Recompile the operating system using buildworld and installworld as described in <URL:http://www.FreeBSD.org/handbook/makeworld.html>. Restart the ntpd(8) daemon, or reboot the system. 3) 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 Note that the patch would disable monitoring features of ntpd(8) daemon by default. If the feature is desirable, the administrator can choose to enable it and firewall access to ntpd(8) service. VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/8/ r260641 releng/8.3/ r260647 releng/8.4/ r260647 stable/9/ r260641 releng/9.1/ r260647 releng/9.2/ r260647 stable/10/ r260639 releng/10.0/ r260641 - ------------------------------------------------------------------------- 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:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References <URL:http://www.symantec.com/connect/blogs/hackers-spend-christmas-break-launching-large-scale-ntp-reflection-attacks> <URL:https://cert.litnet.lt/en/docs/ntp-distributed-reflection-dos-attacks> <URL:http://bugs.ntp.org/show_bug.cgi?id=1532> <URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-5211> The latest revision of this advisory is available at <URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-14:02.ntpd.asc> -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJS1ZTLAAoJEO1n7NZdz2rnn7YP/2DcBtR4LAlMLqa9t8WsFVrD zrfmitYv5xZ6TUGURfQ3mhF4Xv+vSaYt5AWphBjo/Um+dZLTrX3NXJyjLWenCFZ1 vUgoeT4czdh/sWXBO+BdahswttJ6uPO0ZPeW/TpczHMrfG++r6FZtcavYj1gWUPX rQUEh3IRT5MzzcdiIdQFOpi6OeOP7hem5pNOqYwjyy4L4wrgIUetaMpvqXgi2Wa+ R2vqQNpFAPxKkMkbohLEPRmEK9dXGXejQ7EHFK5jzxInyg32WGFPkJ46bLw3bEsB sIoh+sxQ3J9mxyaykhX6T7U7PUkzBaNSs62bQE5H8695E30obnZqtfon6qBP5UCT /kF1+42RIQIPJUFS22NXaUJVOkpd2zyVhwLxgCHg96PHwd1VAC0bnuB4CQt8lN2C vcOsFcq6CUpMuteURBeiETb0OGWTTT3gyX4T7N4kRKptvmEVUKxZPnmfJCwNHM2I TzM2HbHaBv9CMIy5X4iDQxLH3w3tSh+IHU6m9cN5rd6JDTa5DQEuRkhaeVbCGHRt EcSHvUCr+llacITA2rkm1/KPcP97nGgbbM2QbbUVZ/vkdEcImPfrBzrBbaoBzf5p FTplhJ/4bfF0/Kgt5GTNgQXqtIuEQOs+ljNu2HW+cAfX2Hizlo7jjfMxS0y7/fY2 hBdg8zuXs/rBI2LKUcP6 =7q6W -----END PGP SIGNATURE----- _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-security To unsubscribe, send any mail to "[email protected]"