23 December 2016
Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2016.3091 Multiple vulnerabilities of ntp 23 December 2016 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: ntp Publisher: FreeBSD Operating System: FreeBSD Impact/Access: Denial of Service -- Remote/Unauthenticated Access Confidential Data -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2016-9311 CVE-2016-9310 CVE-2016-7434 CVE-2016-7433 CVE-2016-7431 CVE-2016-7428 CVE-2016-7427 CVE-2016-7426 Reference: ESB-2016.3026 ESB-2016.2803 Original Bulletin: https://security.freebsd.org/advisories/FreeBSD-SA-16:39.ntp.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-16:39.ntp Security Advisory The FreeBSD Project Topic: Multiple vulnerabilities of ntp Category: contrib Module: ntp Announced: XXXX-XX-XX Credits: Network Time Foundation Affects: All supported versions of FreeBSD. Corrected: 2016-11-22 16:22:51 UTC (stable/11, 11.0-STABLE) 2016-12-22 16:19:05 UTC (releng/11.0, 11.0-RELEASE-p6) 2016-11-22 16:23:20 UTC (stable/10, 10.3-STABLE) 2016-12-22 16:19:05 UTC (releng/10.3, 10.3-RELEASE-p15) 2016-12-22 16:19:05 UTC (releng/10.2, 10.2-RELEASE-p28) 2016-12-22 16:19:05 UTC (releng/10.1, 10.1-RELEASE-p45) 2016-11-22 16:23:46 UTC (stable/9, 9.3-STABLE) 2016-12-22 16:19:05 UTC (releng/9.3, 9.3-RELEASE-p53) CVE Name: CVE-2016-7426, CVE-2016-7427, CVE-2016-7428, CVE-2016-7431, CVE-2016-7433, CVE-2016-7434, CVE-2016-9310, CVE-2016-9311 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. Trap is a mechanism to collect NTP daemon information from remote. II. Problem Description Multiple vulnerabilities have been discovered in the NTP suite: CVE-2016-9311: Trap crash, Reported by Matthew Van Gundy of Cisco ASIG. CVE-2016-9310: Mode 6 unauthenticated trap information disclosure and DDoS vector. Reported by Matthew Van Gundy of Cisco ASIG. CVE-2016-7427: Broadcast Mode Replay Prevention DoS. Reported by Matthew Van Gundy of Cisco ASIG. CVE-2016-7428: Broadcast Mode Poll Interval Enforcement DoS. Reported by Matthew Van Gundy of Cisco ASIG. CVE-2016-7431: Regression: 010-origin: Zero Origin Timestamp Bypass. Reported by Sharon Goldberg and Aanchal Malhotra of Boston University. CVE-2016-7434: Null pointer dereference in _IO_str_init_static_internal(). Reported by Magnus Stubman. CVE-2016-7426: Client rate limiting and server responses. Reported by Miroslav Lichvar of Red Hat. CVE-2016-7433: Reboot sync calculation problem. Reported independently by Brian Utterback of Oracle, and by Sharon Goldberg and Aanchal Malhotra of Boston University. III. Impact A remote attacker who can send a specially crafted packet to cause a NULL pointer dereference that will crash ntpd, resulting in a Denial of Service. [CVE-2016-9311] An exploitable configuration modification vulnerability exists in the control mode (mode 6) functionality of ntpd. If, against long-standing BCP recommendations, "restrict default noquery ..." is not specified, a specially crafted control mode packet can set ntpd traps, providing information disclosure and DDoS amplification, and unset ntpd traps, disabling legitimate monitoring by an attacker from remote. [CVE-2016-9310] An attacker with access to the NTP broadcast domain can periodically inject specially crafted broadcast mode NTP packets into the broadcast domain which, while being logged by ntpd, can cause ntpd to reject broadcast mode packets from legitimate NTP broadcast servers. [CVE-2016-7427] An attacker with access to the NTP broadcast domain can send specially crafted broadcast mode NTP packets to the broadcast domain which, while being logged by ntpd, will cause ntpd to reject broadcast mode packets from legitimate NTP broadcast servers. [CVE-2016-7428] Origin timestamp problems were fixed in ntp 4.2.8p6. However, subsequent timestamp validation checks introduced a regression in the handling of some Zero origin timestamp checks. [CVE-2016-7431] If ntpd is configured to allow mrulist query requests from a server that sends a crafted malicious packet, ntpd will crash on receipt of that crafted malicious mrulist query packet. [CVE-2016-7434] An attacker who knows the sources (e.g., from an IPv4 refid in server response) and knows the system is (mis)configured in this way can periodically send packets with spoofed source address to keep the rate limiting activated and prevent ntpd from accepting valid responses from its sources. [CVE-2016-7426] Ntp Bug 2085 described a condition where the root delay was included twice, causing the jitter value to be higher than expected. Due to a misinterpretation of a small-print variable in The Book, the fix for this problem was incorrect, resulting in a root distance that did not include the peer dispersion. The calculations and formulas have been reviewed and reconciled, and the code has been updated accordingly. [CVE-2016-7433] 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-16:39/ntp-11.0.patch # fetch https://security.FreeBSD.org/patches/SA-16:39/ntp-11.0.patch.asc # gpg --verify ntp-11.0.patch.asc [FreeBSD 10.x] # fetch https://security.FreeBSD.org/patches/SA-16:39/ntp-10.x.patch # fetch https://security.FreeBSD.org/patches/SA-16:39/ntp-10.x.patch.asc # gpg --verify ntp-10.x.patch.asc [FreeBSD 9.3] # fetch https://security.FreeBSD.org/patches/SA-16:39/ntp-9.3.patch # fetch https://security.FreeBSD.org/patches/SA-16:39/ntp-9.3.patch.asc # gpg --verify ntp-9.3.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/9/ r309009 releng/9.3/ r310419 stable/10/ r309008 releng/10.1/ r310419 releng/10.2/ r310419 releng/10.3/ r310419 stable/11/ r309007 releng/11.0/ r310419 - - ------------------------------------------------------------------------- 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#November_2016_ntp_4_2_8p9_NTP_Se> <URL:https://www.kb.cert.org/vuls/id/633847> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7426> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7427> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7428> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7431> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7433> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7434> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-9310> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-9311> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-16:39.ntp.asc> - -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.1.16 (FreeBSD) iQIzBAEBCgAdFiEEHPf/b631yp++G4yy7Wfs1l3PaucFAlhb/kAACgkQ7Wfs1l3P audQRhAA02Xpoz4mSF1Cz1gCgWAKpTNpB2fG5z8Pqv1q8BqdArr+ZH/G1g2L4E/b Id/g8WUvpZLozTeuWMx/6dm/XCbI+OhbzasZp46Cak3o2LMB6v3OC43qVX8fQiiO 9GgCltR6I8V939MVFKxo+cdflqIwmguKdLJHvnin8mv8MAjXOG7rrAx+FqcQjJ5i oATuFLj/A9kWDiRH4TAQr/rVRmJGmIQY2GpEMt7oB/1ho5HFGhIdNZLCuriIcAGZ HpZJoNKmDHV3mOfM+C03e4otBaoX6asid2TiY5lnDMx4j+a+Gxdv5tWnt72Bn0X/ EC5HWYjm7QFDg/hfrymBfT7cObuVKtdEJikkRw3huBy6RN6d4zsaTJFMIODl6sNs zBE5+vrwcXiUrbic10RoVzeSEFdVh7C6Ji1OK/rsxXAbgs0zkoHua/nxO2fhdyHr m3Mb59QE7TiM1zaMjks1QZXORo53CrGHrhE6Qi7sISO0SS4mWCOkulOZeNjXQ3xK GFox3YV0WDZz4m7VjZQS6/pj+dO4sABVQ0mahydJJX35FVkdJuknv/98yxmYRuHG jP9NTUEh6dGDT3w/57hGg7VIgTR47q3e6UbutrqNoxiV5Br465mb9LxMjngDW7bA poe9XHFMCmFV96gYN2va2cENUM/PjWI8mHWjZShG5DCXMVnK64A= =PDXk - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. 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