Good news/bad news.
The good news is that I like to think I did a better job describing this
problem than I have done in the past.
The bad news is that I think I did a pretty sucky job of describing this
problem in our report.
Y'all did a much better job of this than I did.
The NTP Project has had maybe 3 of these sort of issues in the past 15+
years, so I don't have much experience in dealing with writing the
announcements.
Might I be able to work with y'all on any future similar security
advisories so our security announcements are better?
H
--
Harlan Stenn st...@ntp.org
http://ntpforum.isc.org - be a member!
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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/UPDATING1.416.2.37.2.14
src/sys/conf/newvers.sh
