-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-10:02.ntpd Security Advisory The FreeBSD Project Topic: ntpd mode 7 denial of service Category: contrib Module: ntpd Announced: 2010-01-06 Affects: All supported versions of FreeBSD. Corrected: 2010-01-06 21:45:30 UTC (RELENG_8, 8.0-STABLE) 2010-01-06 21:45:30 UTC (RELENG_8_0, 8.0-RELEASE-p2) 2010-01-06 21:45:30 UTC (RELENG_7, 7.2-STABLE) 2010-01-06 21:45:30 UTC (RELENG_7_2, 7.2-RELEASE-p6) 2010-01-06 21:45:30 UTC (RELENG_7_1, 7.1-RELEASE-p10) 2010-01-06 21:45:30 UTC (RELENG_6, 6.4-STABLE) 2010-01-06 21:45:30 UTC (RELENG_6_4, 6.4-RELEASE-p9) 2010-01-06 21:45:30 UTC (RELENG_6_3, 6.3-RELEASE-p15) CVE Name: CVE-2009-3563 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 If ntpd receives a mode 7 (MODE_PRIVATE) request or error response from a source address not listed in either a 'restrict ... noquery' or a 'restrict ... ignore' section it will log the even and send a mode 7 error response. III. Impact If an attacker can spoof such a packet from a source IP of an affected ntpd to the same or a different affected ntpd, the host(s) will endlessly send error responses to each other and log each event, consuming network bandwidth, CPU and possibly disk space. IV. Workaround Proper filtering of mode 7 NTP packets by a firewall can limit the number of systems used to attack your resources. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to 6-STABLE, 7-STABLE or 8-STABLE, or to the RELENG_8_0, RELENG_7_2, RELENG_7_1, RELENG_6_4, or RELENG_6_3 security branch dated after the correction date. 2) To patch your present system: The following patches have been verified to apply to FreeBSD 6.3, 6.4, 7.1, 7.2, and 8.0 systems. 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-10:02/ntpd.patch # fetch http://security.FreeBSD.org/patches/SA-10:02/ntpd.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch # cd /usr/src/usr.sbin/ntp/ntpd # make obj && make depend && make && make install # /etc/rc.d/ntpd restart VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. CVS: Branch Revision Path - ------------------------------------------------------------------------- RELENG_6 src/contrib/ntp/ntpd/ntp_request.c 1.1.1.4.8.2 RELENG_6_4 src/UPDATING 1.416.2.40.2.13 src/sys/conf/newvers.sh 1.69.2.18.2.15 src/contrib/ntp/ntpd/ntp_request.c 1.1.1.4.8.1.2.1 RELENG_6_3 src/UPDATING 1.416.2.37.2.20 src/sys/conf/newvers.sh 1.69.2.15.2.19 src/contrib/ntp/ntpd/ntp_request.c 1.1.1.4.20.1 RELENG_7 src/contrib/ntp/ntpd/ntp_request.c 1.1.1.4.18.2 RELENG_7_2 src/UPDATING 1.507.2.23.2.9 src/sys/conf/newvers.sh 1.72.2.11.2.10 src/contrib/ntp/ntpd/ntp_request.c 1.1.1.4.18.1.4.1 RELENG_7_1 src/UPDATING 1.507.2.13.2.13 src/sys/conf/newvers.sh 1.72.2.9.2.14 src/contrib/ntp/ntpd/ntp_request.c 1.1.1.4.18.1.2.1 RELENG_8 src/contrib/ntp/ntpd/ntp_request.c 1.2.2.1 RELENG_8_0 src/UPDATING 1.632.2.7.2.5 src/sys/conf/newvers.sh 1.83.2.6.2.5 src/contrib/ntp/ntpd/ntp_request.c 1.2.4.1 - ------------------------------------------------------------------------- Subversion: Branch/path Revision - ------------------------------------------------------------------------- stable/6/ r201679 releng/6.4/ r201679 releng/6.3/ r201679 stable/7/ r201679 releng/7.2/ r201679 releng/7.1/ r201679 stable/8/ r201679 releng/8.0/ r201679 head/ r200576 - ------------------------------------------------------------------------- VII. References http://support.ntp.org/bin/view/Main/SecurityNotice#DoS_attack_from_certain_NTP_mode https://support.ntp.org/bugs/show_bug.cgi?id=1331 http://www.kb.cert.org/vuls/id/568372 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-3563 The latest revision of this advisory is available at http://security.FreeBSD.org/advisories/FreeBSD-SA-10:02.ntpd.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iD8DBQFLRQ9gFdaIBMps37IRAuH1AJ9eOII8McK5332jhuBHEMxAUbWKNQCghYfs y66+ElAr2uZrrXwerlVETPc= =yJm1 -----END PGP SIGNATURE-----