FreeBSD Security Advisory FreeBSD-SA-16:24.ntp

Fabricante: FreeBSD
Fecha: 04/06/2016
Identificador: FreeBSD-SA-16:24.ntp
FreeBSD Security Advisory FreeBSD-SA-16:24.ntp
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-16:24.ntp Security Advisory The FreeBSD Project Topic: Multiple vulnerabilities of ntp Category: contrib Module: ntp Announced: 2016-06-04 Credits: Network Time Foundation and various contributors listed below Affects: All supported versions of FreeBSD. Corrected: 2016-06-03 08:59:21 UTC (stable/10, 10.3-STABLE) 2016-06-04 05:46:52 UTC (releng/10.3, 10.3-RELEASE-p5) 2016-06-04 05:46:52 UTC (releng/10.2, 10.2-RELEASE-p19) 2016-06-04 05:46:52 UTC (releng/10.1, 10.1-RELEASE-p36) 2016-06-03 09:03:10 UTC (stable/9, 9.3-STABLE) 2016-06-04 05:46:52 UTC (releng/9.3, 9.3-RELEASE-p44) CVE Name: CVE-2016-4957, CVE-2016-4953, CVE-2016-4954, CVE-2016-4955 CVE-2016-4956 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . 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 Multiple vulnerabilities have been discovered in the NTP suite: The fix for Sec 3007 in ntp-4.2.8p7 contained a bug that could cause ntpd to crash. [CVE-2016-4957, Reported by Nicolas Edet of Cisco] An attacker who knows the origin timestamp and can send a spoofed packet containing a CRYPTO-NAK to an ephemeral peer target before any other response is sent can demobilize that association. [CVE-2016-4953, Reported by Miroslav Lichvar of Red Hat] An attacker who is able to spoof packets with correct origin timestamps from enough servers before the expected response packets arrive at the target machine can affect some peer variables and, for example, cause a false leap indication to be set. [CVE-2016-4954, Reported by Jakub Prokes of Red Hat] An attacker who is able to spoof a packet with a correct origin timestamp before the expected response packet arrives at the target machine can send a CRYPTO_NAK or a bad MAC and cause the association's peer variables to be cleared. If this can be done often enough, it will prevent that association from working. [CVE-2016-4955, Reported by Miroslav Lichvar of Red Hat] The fix for NtpBug2978 does not cover broadcast associations, so broadcast clients can be triggered to flip into interleave mode. [CVE-2016-4956, Reported by Miroslav Lichvar of Red Hat.] III. Impact Malicious remote attackers may be able to break time synchronization, or cause the ntpd(8) daemon to crash. 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 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. # fetch https://security.FreeBSD.org/patches/SA-16:24/ntp.patch # fetch https://security.FreeBSD.org/patches/SA-16:24/ntp.patch.asc # gpg --verify ntp.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 . 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/9/ r301257 releng/9.3/ r301301 stable/10/ r301256 releng/10.1/ r301301 releng/10.2/ r301301 releng/10.3/ r301301 - ------------------------------------------------------------------------- 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: VII. References The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.1.12 (FreeBSD) iQIcBAEBCgAGBQJXUnRyAAoJEO1n7NZdz2rncMMQAIB69xMkhWqoZ+0R2R6MOPAI UWIEPN4fLktiz4oIKP/C/xTsJdonC6+GCKbEb4h+deUOEYPaK5L1RsjvzwjqDKvI 9THtZUBoEcifALOiO1Mkum+1ntCkF+7EK2EXSuF2/wYga/ekVkCPZqLxmUEbL/KG HEa4VCnMv0euAxEbtzix6efNTZV/9O0uUmYlU0wt8WF+YL+p15CyhBIc5YZISpWA izugcLKU8xriFMOiyOIttnIS1pAKERu0Fh9EqlkfFhcmJXl18Oxn10L0qH6uEx/C Rs11KzyJSuOpBl7x5NZi9jsTzlZlI6zqJ9b6Dlj2A8k82oz5p3VUf+CDyDlMZxHo 2PsRPGdYJA98w/dUFucZozt1J4K05dWOnd6oED1bY8bFEb+IhRYYOil/wqiNBJFw Q9B6jB18Olp4PxxMZVX5kXz4j3tzqlt80wY9S/pVOIGjKcbxIHqhB5CFt1UJfsUw BGzJTpYYBvqdS0e3ozO+4QyHBlm4Ure4JFlrb/kBXgLvnBcTfn5e2NMJKhMSvC0B O5Ma1D7E2eYxxHgpUFTJYo+qNrfWsQHPClxOMVXbxUrz/iheEvTaed7tyHtMI5nz vloTNWf4WNWnxYv5meOOSj2lXX5dxT+XpEA+1kmOWdWvOx8nmOWrOUYN6hM191jD e3hZ2X6TAfHd5LIHtb2C =ttlK -----END PGP SIGNATURE-----