SecurityTracker.com
    Home    |    View Topics    |    Search    |    Contact Us    |   

SecurityTracker
Archives


 


Category:   Application (Generic)  >   ntp Vendors:   ntp.org
(FreeBSD Issues Fix) NTP Signature Validation Flaw Lets Remote Users Bypass Validation Checks
SecurityTracker Alert ID:  1021573
SecurityTracker URL:  http://securitytracker.com/id/1021573
CVE Reference:   CVE-2009-0021   (Links to External Site)
Date:  Jan 14 2009
Impact:   Disclosure of authentication information
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 4.2.4p5 (production) and prior versions; 4.2.5p150 (development) and prior versions
Description:   A vulnerability was reported in NTP. A remote user can bypass digital signature validation.

The software does not properly check the results of the OpenSSL EVP_VerifyFinal() function. As a result, a remote server can supply a specially crafted invalid signature on a certificate that will be detected as a valid certificate. Signature checks on DSA and ECDSA keys used with SSL/TLS are affected.

Clients that connect to servers using RSA keys are not affected.

Client certificate validation is not affected.

Impact:   A remote user can bypass certificate validation.
Solution:   FreeBSD has released a fix and has provided the following solution instructions [quoted].

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

The FreeBSD advisory is available at:

http://security.FreeBSD.org/advisories/FreeBSD-SA-09:03.ntpd.asc

Vendor URL:  www.ntp.org/ (Links to External Site)
Cause:   State error
Underlying OS:  UNIX (FreeBSD)
Underlying OS Comments:  6.3, 6.4, 7.0, 7.1

Message History:   This archive entry is a follow-up to the message listed below.
Jan 7 2009 NTP Signature Validation Flaw Lets Remote Users Bypass Validation Checks



 Source Message Contents

Subject:  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-----
_______________________________________________
freebsd-security-notifications@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-security-notifications
To unsubscribe, send any mail to "freebsd-security-notifications-unsubscribe@freebsd.org"

 
 


Go to the Top of This SecurityTracker Archive Page





Home   |    View Topics   |    Search   |    Contact Us

This web site uses cookies for web analytics. Learn More

Copyright 2022, SecurityGlobal.net LLC