FreeBSD Security Advisories
2009-Jan-13 14:33 UTC
FreeBSD Security Advisory FreeBSD-SA-09:03.ntpd
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================FreeBSD-SA-09:03.ntpd Security Advisory The FreeBSD Project Topic: ntpd cryptographic signature bypass Category: contrib Module: ntpd Announced: 2009-01-13 Credits: Google Security Team Affects: All FreeBSD releases Corrected: 2009-01-13 21:19:27 UTC (RELENG_7, 7.1-STABLE) 2009-01-13 21:19:27 UTC (RELENG_7_1, 7.1-RELEASE-p2) 2009-01-13 21:19:27 UTC (RELENG_7_0, 7.0-RELEASE-p9) 2009-01-13 21:19:27 UTC (RELENG_6, 6.4-STABLE) 2009-01-13 21:19:27 UTC (RELENG_6_4, 6.4-RELEASE-p3) 2009-01-13 21:19:27 UTC (RELENG_6_3, 6.3-RELEASE-p9) CVE Name: CVE-2009-0021 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 daemon is an implementation of the Network Time Protocol (NTP) used to synchronize the time of a computer system to a reference time source. FreeBSD includes software from the OpenSSL Project. The OpenSSL Project is a collaborative effort to develop a robust, commercial-grade, full-featured Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library. II. Problem Description The EVP_VerifyFinal() function from OpenSSL is used to determine if a digital signature is valid. When ntpd(8) is set to cryptographically authenticate NTP data it incorrectly checks the return value from EVP_VerifyFinal(). III. Impact An attacker which can send NTP packets to ntpd, which uses cryptographic authentication of NTP data, may be able to inject malicious time data causing the system clock to be set incorrectly. IV. Workaround Use IP based restrictions in ntpd itself or in IP firewalls to restrict which systems can send NTP packets to ntpd. NOTE WELL: If ntpd is not explicitly set to use cryptographic authentication of NTP data the setup is not vulnerable to the issue as described in this Security Advisory. V. Solution NOTE WELL: Due to an error in building the updates, this fix is not available via freebsd-update at the time of this advisory. We expect that this will be fixed within the next 48 hours. Perform one of the following: 1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the RELENG_7_1, RELENG_7_0, 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, 7.0, and 7.1 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 6.4 and 7.1] # fetch http://security.FreeBSD.org/patches/SA-09:03/ntpd.patch # fetch http://security.FreeBSD.org/patches/SA-09:03/ntpd.patch.asc [FreeBSD 6.3 and 7.0] # fetch http://security.FreeBSD.org/patches/SA-09:03/ntpd63.patch # fetch http://security.FreeBSD.org/patches/SA-09:03/ntpd63.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_crypto.c 1.1.1.3.8.2 RELENG_6_4 src/UPDATING 1.416.2.40.2.6 src/sys/conf/newvers.sh 1.69.2.18.2.9 src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.8.1.2.1 RELENG_6_3 src/UPDATING 1.416.2.37.2.14 src/sys/conf/newvers.sh 1.69.2.15.2.13 src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.20.1 RELENG_7 src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.18.2 RELENG_7_1 src/UPDATING 1.507.2.13.2.5 src/sys/conf/newvers.sh 1.72.2.9.2.6 src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.18.1.2.1 RELENG_7_0 src/UPDATING 1.507.2.3.2.13 src/sys/conf/newvers.sh 1.72.2.5.2.13 src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.22.1 - ------------------------------------------------------------------------- Subversion: Branch/path Revision - ------------------------------------------------------------------------- stable/6/ r187194 releng/6.4/ r187194 releng/6.3/ r187194 stable/7/ r187194 releng/7.1/ r187194 releng/7.0/ r187194 - ------------------------------------------------------------------------- VII. References http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-0021 http://security.FreeBSD.org/advisories/FreeBSD-SA-09:02.openssl.asc The latest revision of this advisory is available at http://security.FreeBSD.org/advisories/FreeBSD-SA-09:03.ntpd.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iD8DBQFJbRUfFdaIBMps37IRAqdjAJ42YSH0bjaAJBEVyMM7/em/tu0xUQCfVPrs IrH0Qxo4slvboQHsy1PbkN4=Q4rn -----END PGP SIGNATURE-----