FreeBSD Security Advisory FreeBSD-SA-18:02.ntp
7 March, 2018 by email@example.com | freebsd
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-18:02.ntp Security Advisory The FreeBSD Project Topic: Multiple vulnerabilities of ntp Category: contrib Module: ntp Announced: 2018-03-07 Credits: Network Time Foundation Affects: All supported versions of FreeBSD. Corrected: 2018-02-28 09:01:03 UTC (stable/11, 11.1-STABLE) 2018-03-07 05:58:24 UTC (releng/11.1, 11.1-RELEASE-p7) 2018-03-01 04:06:49 UTC (stable/10, 10.4-STABLE) 2018-03-07 05:58:24 UTC (releng/10.4, 10.4-RELEASE-p6) 2018-03-07 05:58:24 UTC (releng/10.3, 10.3-RELEASE-p27) CVE Name: CVE-2018-7182, CVE-2018-7170, CVE-2018-7184, CVE-2018-7185, CVE-2018-7183 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 The ctl_getitem() function is used by ntpd(8) to process incoming "mode 6" packets. A malicious "mode 6" packet can be sent to an ntpd instance, and if the ntpd instance is from 4.2.8p6 through 4.2.8p10, ctl_getitem() will read past the end of its buffer. [CVE-2018-7182] The ntpd(8) service can be vulnerable to Sybil attacks. If a system is configured to use a trustedkey and if one is not using the feature introduced in ntp-4.2.8p6 allowing an optional 4th field in the ntp.keys file to specify which IPs can serve time, a malicious authenticated peer, i.e., one where the attacker knows the private symmetric key, can create arbitrarily-many ephemeral associations in order to win the clock selection of ntpd and modify a victim's clock. [CVE-2018-7170] The fix for NtpBug2952 was incomplete, and while it fixed one problem it created another. Specifically, it drops bad packets before updating the "received" timestamp. This means a third-party can inject a packet with a zero-origin timestamp, meaning the sender wants to reset the association, and the transmit timestamp in this bogus packet will be saved as the most recent "received" timestamp. The real remote peer does not know this value and this will disrupt the association until the association resets. [CVE-2018-7184] The NTP Protocol allows for both non-authenticated and authenticated associations, in client/server, symmetric (peer), and several broadcast modes. In addition to the basic NTP operational modes, symmetric mode and broadcast servers can support an interleaved mode of operation. In ntp-4.2.8p4, a bug was inadvertently introduced into the protocol engine that allows a non-authenticated zero-origin (reset) packet to reset an authenticated interleaved peer association. If an attacker can send a packet with a zero-origin timestamp and the source IP address of the "other side" of an interleaved association, the 'victim' ntpd will reset its association. The attacker must continue sending these packets in order to maintain the disruption of the association. [CVE-2018-7185] The ntpq(8) utility is a monitoring and control program for ntpd. The internal decodearr() function of ntpq(8) that is used to decode an array in a response string when formatted data is being displayed. This is a problem in affected versions of ntpq if a maliciously-altered ntpd returns an array result that will trip this bug, or if a bad actor is able to read an ntpq(8) request on its way to a remote ntpd server and forge and send a response before the remote ntpd sends its response. It is potentially possible that the malicious data could become injectable/executable code. [CVE-2017-7183] III. Impact Malicious remote attackers may be able to break time synchornization, or cause the ntpq(8) utility to crash. IV. Workaround No workaround is available, but systems not running ntpd(8) or ntpq(8) are not affected. Network administrators are advised to implement BCP-38 which helps to reduce risk associated with the 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 11.1] # fetch https://security.FreeBSD.org/patches/SA-18:02/ntp-11.1.patch # fetch https://security.FreeBSD.org/patches/SA-18:02/ntp-11.1.patch.asc # gpg --verify ntp-11.1.patch.asc [FreeBSD 10.4] # fetch https://security.FreeBSD.org/patches/SA-18:02/ntp-10.4.patch # fetch https://security.FreeBSD.org/patches/SA-18:02/ntp-10.4.patch.asc # gpg --verify ntp-10.4.patch.asc [FreeBSD 10.3] # fetch https://security.FreeBSD.org/patches/SA-18:02/ntp-10.3.patch # fetch https://security.FreeBSD.org/patches/SA-18:02/ntp-10.3.patch.asc # gpg --verify ntp-10.3.patch.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/ r330141 releng/10.3/ r330567 releng/10.4/ r330567 stable/11/ r330106 releng/11.1/ r330567 - ------------------------------------------------------------------------- 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:http://support.ntp.org/bin/view/Main/SecurityNotice#February_2018_ntp_4_2_8p11_NTP_S> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-7182> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-7170> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-7184> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-7185> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-7183> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-18:02.ntp.asc> -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAlqfhYNfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cL9GQ/+PLffyegsvxKngL83XWG9UuHbcGG5aWbNwCecTEzNoCI72TI03aga0ge5 iLz5kW3SQvl8tsq778U4YbfFcCw6ifq2ws8asqNviv+u4AcJh7oD8CS3/kFuA9xM zjAIrScdNR2taBJhBW3nwlb7RmDeKqydQ3OIxHVvs9Fj5Alc5ZEGezUjC2dueB+M UdORg6GvHGMYQ+4AtBFRgZHAU3BFkwmgqsIICywYnUVH+AxKj34shs/pMMeJd/d9 a+BIu/tUjAIlQp23VunNAfq7r2eZik9LOV8Y5l1Ww7+K1IwlwezxI+Iw18BMFEVn L9baBY9RFh8v/yrZCBqUc7Prhs3ExU/lnAb05Va7TYeD4RXVmSU0jNXi/przN3y2 PR7Z3JCm60mFKyp0/Hz2MmS1XPBVBrW4P6g9hH8TZmOHb2mZlK3zDXmil7HKp5DK UhtMJpPEWV9k5rfP8iijHJnwkPr0ALntMUAAKUyw/6isVtHT6BZLaYsZvRYIm8YY Mn2RUl74m+XoIhQ8R4mxRcaAHwKKXyeyP5nlAs6TQVb9QJukoRiNDr3g8TwbtT54 iTswVu+z/a89/YIwJoc6Ud7eCZSDYe6qfuC19TVuledayjjy/ZPMH0ZkNWFWJ3AE VAvdyvoUuNbmsv42o4AUtpE/1CmDqOjwBRZZbtV4CONCDFpk26o= =D2ov -----END PGP SIGNATURE----- _______________________________________________ firstname.lastname@example.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-announce To unsubscribe, send any mail to "email@example.com"