(FreeBSD Issues Fix) ntp Bugs Let Remote Users Deny Service, Obtain Potentially Sensitive Information, and Bypass Access Controls in Certain Cases
SecurityTracker Alert ID: 1032036|
SecurityTracker URL: http://securitytracker.com/id/1032036
(Links to External Site)
Updated: Nov 4 2015|
Original Entry Date: Apr 7 2015
Denial of service via network, Disclosure of system information, Disclosure of user information|
Fix Available: Yes Vendor Confirmed: Yes |
Version(s): prior to 4.2.8p1|
Two vulnerabilities were reported in ntp. A remote user can cause denial of service conditions. A remote user can obtain potentially sensitive information. A remote user can bypass access controls in certain cases.|
A remote user can send a specially crafted 'vallen' parameter value to trigger a validation flaw in 'ntp_crypto.c' and obtain potentially sensitive information or cause the target ntpd service to crash [CVE-2014-9750].
Stephen Roettger of the Google Security Team, Sebastian Krahmer of the SUSE Security Team, and Harlan Stenn of Network Time Foundation reported this vulnerability.
A remote user may be able to spoof the ::1 source address via IPv6 to bypass IPv6-based access controls [CVE-2014-9751]. Some operating systems are affected, including Apple OS X and Linux.
Stephen Roettger of the Google Security Team reported this vulnerability.
A remote user can cause denial of service conditions.|
A remote user can obtain potentially sensitive information.
A remote user can bypass access controls in certain cases.
FreeBSD has issued a fix for CVE-2014-9750.|
[Editor's note: On November 4, 2015, FreeBSD issued a revised advisory to announce new patches to fix a regression error. Users that have applied the original fix should apply the new incremental fix.]
The FreeBSD advisory is available at:
Vendor URL: support.ntp.org/bin/view/Main/SecurityNotice#vallen_is_not_validated_in_sever (Links to External Site)
Access control error|
|Underlying OS: UNIX (FreeBSD)|
|Underlying OS Comments: 8.4, 9.3, 10.1|
This archive entry is a follow-up to the message listed below.|
Source Message Contents
Subject: FreeBSD Security Advisory FreeBSD-SA-15:07.ntp|
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FreeBSD-SA-15:07.ntp Security Advisory
The FreeBSD Project
Topic: Multiple vulnerabilities of ntp
Credits: Network Time Foundation
Affects: All supported versions of FreeBSD.
Corrected: 2015-04-07 20:20:24 UTC (stable/10, 10.1-STABLE)
2015-04-07 20:21:01 UTC (releng/10.1, 10.1-RELEASE-p9)
2015-04-07 20:20:44 UTC (stable/9, 9.3-STABLE)
2015-04-07 20:21:23 UTC (releng/9.3, 9.3-RELEASE-p13)
2015-04-07 20:20:44 UTC (stable/8, 8.4-STABLE)
2015-04-07 20:21:23 UTC (releng/8.4, 8.4-RELEASE-p27)
CVE Name: CVE-2014-9297, CVE-2015-1798, CVE-2015-1799
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:https://security.FreeBSD.org/>.
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
II. Problem Description
The vallen packet value is not validated in several code paths in
When ntpd(8) is configured to use a symmetric key to authenticate a remote
NTP server/peer, it checks if the NTP message authentication code (MAC)
in received packets is valid, but not that there actually is any MAC
included, and packets without a MAC are accepted as if they had a valid
NTP state variables are updated prior to validating the received packets.
A remote attacker who can send specifically crafted packets may be able
to reveal memory contents of ntpd(8) or cause it to crash, when ntpd(8)
is configured to use autokey. [CVE-2014-9297]
A man-in-the-middle (MITM) attacker can send specially forged packets
that would be accepted by the client/peer without having to know the
symmetric key. [CVE-2015-1798]
An attacker knowing that NTP hosts A and B are peering with each other
(symmetric association) can periodically send a specially crafted or
replayed packet which will break the synchronization between the two
peers due to transmit timestamp mismatch, preventing the two nodes from
synchronizing with each other, even when authentication is enabled.
No workaround is available, but systems not running ntpd(8) are not
Perform one of the following:
1) Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date.
2) To update your vulnerable system via a binary patch:
Systems running a RELEASE version of FreeBSD on the i386 or amd64
platforms can be updated via the freebsd-update(8) utility:
# freebsd-update fetch
# freebsd-update install
3) To update your vulnerable system via a source code patch:
The following patches have been verified to apply to the applicable
FreeBSD release branches.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
# fetch https://security.FreeBSD.org/patches/SA-15:07/ntp.patch
# fetch https://security.FreeBSD.org/patches/SA-15:07/ntp.patch.asc
# gpg --verify ntp.patch.asc
b) Apply the patch. Execute the following commands as root:
# cd /usr/src
# patch < /path/to/patch
c) Recompile the operating system using buildworld and installworld as
described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.
Restart the applicable daemons, or reboot the system.
VI. Correction details
The following list contains the correction revision numbers for each
To see which files were modified by a particular revision, run the
following command, replacing NNNNNN with the revision number, on a
machine with Subversion installed:
# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
Or visit the following URL, replacing NNNNNN with the revision number:
The latest revision of this advisory is available at
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