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Posted on 10 June 2009
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FreeBSD-SA-09:11.ntpd Security Advisory
The FreeBSD Project
Topic: ntpd stack-based buffer-overflow vulnerability
Category: contrib
Module: ntpd
Announced: 2009-06-10
Credits: Chris Ries
Affects: All supported versions of FreeBSD.
Corrected: 2009-06-10 10:31:11 UTC (RELENG_7, 7.2-STABLE)
2009-06-10 10:31:11 UTC (RELENG_7_2, 7.2-RELEASE-p1)
2009-06-10 10:31:11 UTC (RELENG_7_1, 7.1-RELEASE-p6)
2009-06-10 10:31:11 UTC (RELENG_6, 6.4-STABLE)
2009-06-10 10:31:11 UTC (RELENG_6_4, 6.4-RELEASE-p5)
2009-06-10 10:31:11 UTC (RELENG_6_3, 6.3-RELEASE-p11)
CVE Name: CVE-2009-1252
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(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.
Autokey is a security model for authenticating Network Time Protocol
(NTP) servers to clients, using public key cryptography.
II. Problem Description
The ntpd(8) daemon is prone to a stack-based buffer-overflow when it is
configured to use the 'autokey' security model.
III. Impact
This issue could be exploited to execute arbitrary code in the context of
the service daemon, or crash the service daemon, causing denial-of-service
conditions.
IV. Workaround
Use IP based restrictions in ntpd(8) itself or in IP firewalls to
restrict which systems can send NTP packets to ntpd(8).
Note that systems will only be affected if they have the "autokey" option
set in /etc/ntp.conf; FreeBSD does not ship with a default ntp.conf file,
so will not be affected unless this option has been explicitly enabled by
the system administrator.
V. Solution
Perform one of the following:
1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the
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, and 7.2 systems.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
[FreeBSD 6.3]
# fetch http://security.FreeBSD.org/patches/SA-09:11/ntpd63.patch
# fetch http://security.FreeBSD.org/patches/SA-09:11/ntpd63.patch.asc
[FreeBSD 6.4 and 7.x]
# fetch http://security.FreeBSD.org/patches/SA-09:11/ntpd.patch
# fetch http://security.FreeBSD.org/patches/SA-09:11/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_crypto.c 1.1.1.3.8.3
RELENG_6_4
src/UPDATING 1.416.2.40.2.9
src/sys/conf/newvers.sh 1.69.2.18.2.11
src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.8.1.2.2
RELENG_6_3
src/UPDATING 1.416.2.37.2.16
src/sys/conf/newvers.sh 1.69.2.15.2.15
src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.20.2
RELENG_7
src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.18.3
RELENG_7_2
src/UPDATING 1.507.2.23.2.4
src/sys/conf/newvers.sh 1.72.2.11.2.5
src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.18.2.2.1
RELENG_7_1
src/UPDATING 1.507.2.13.2.9
src/sys/conf/newvers.sh 1.72.2.9.2.10
src/contrib/ntp/ntpd/ntp_crypto.c 1.1.1.3.18.1.2.2
- -------------------------------------------------------------------------
Subversion:
Branch/path Revision
- -------------------------------------------------------------------------
stable/6/ r193893
releng/6.4/ r193893
releng/6.3/ r193893
stable/7/ r193893
releng/7.2/ r193893
releng/7.1/ r193893
- -------------------------------------------------------------------------
VII. References
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1252
The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-09:11.ntpd.asc
