FreeBSD Security Advisory FreeBSD-SA-14:31.ntp

Type securityvulns
Reporter Securityvulns
Modified 2014-12-25T00:00:00



============================================================================= FreeBSD-SA-14:31.ntp Security Advisory The FreeBSD Project

Topic: Multiple vulnerabilities in NTP suite

Category: contrib Module: ntp Announced: 2014-12-23 Affects: All supported versions of FreeBSD. Corrected: 2014-14-22 19:07:16 UTC (stable/10, 10.1-STABLE) 2014-12-23 22:56:01 UTC (releng/10.1, 10.1-RELEASE-p3) 2014-12-23 22:55:14 UTC (releng/10.0, 10.0-RELEASE-p15) 2014-14-22 19:08:09 UTC (stable/9, 9.3-STABLE) 2014-12-23 22:54:25 UTC (releng/9.3, 9.3-RELEASE-p7) 2014-12-23 22:53:44 UTC (releng/9.2, 9.2-RELEASE-p17) 2014-12-23 22:53:03 UTC (releng/9.1, 9.1-RELEASE-p24) 2014-14-22 19:08:09 UTC (stable/8, 8.4-STABLE) 2014-12-23 22:52:22 UTC (releng/8.4, 8.4-RELEASE-p21) CVE Name: CVE-2014-9293, CVE-2014-9294, CVE-2014-9295, CVE-2014-9296

For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:>.

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.

II. Problem Description

When no authentication key is set in the configuration file, ntpd(8) would generate a random key that uses a non-linear additive feedback random number generator seeded with very few bits of entropy. [CVE-2014-9293] The ntp-keygen(8) utility is also affected by a similar issue. [CVE-2014-9294]

When Autokey Authentication is enabled, for example if ntp.conf(5) contains a 'crypto pw' directive, a remote attacker can send a carefully crafted packet that can overflow a stack buffer. [CVE-2014-9295]

In ntp_proto.c, the receive() function is missing a return statement in the case when an error is detected. [CVE-2014-9296]

III. Impact

The NTP protocol uses keys to implement authentication. The weak seeding of the pseudo-random number generator makes it easier for an attacker to brute-force keys, and thus may broadcast incorrect time stamps or masquerade as another time server. [CVE-2014-9293, CVE-2014-9294]

An attacker may be able to utilize the buffer overflow to crash the ntpd(8) daemon or potentially run arbitrary code with the privileges of the ntpd(8) process, which is typically root. [CVE-2014-9295]

IV. Workaround

No workaround is available, but systems not running ntpd(8) are not affected. Because the issue may lead to remote root compromise, the FreeBSD Security Team recommends system administrators to firewall NTP ports, namely tcp/123 and udp/123 when it is not clear that all systems have been patched or have ntpd(8) stopped.

V. Solution

NOTE WELL: It is advisable to regenerate all keys used for NTP authentication, if configured.

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.



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:>.

Restart the ntpd(8) daemons, or reboot the system.

VI. Correction details

The following list contains the correction revision numbers for each affected branch.

Branch/path Revision

stable/8/ r276073 releng/8.4/ r276154 stable/9/ r276073 releng/9.1/ r276155 releng/9.2/ r276156 releng/9.3/ r276157 stable/10/ r276072 releng/10.0/ r276158 releng/10.1/ r276159

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://

Or visit the following URL, replacing NNNNNN with the revision number:


VII. References






The latest revision of this advisory is available at <URL:> -----BEGIN PGP SIGNATURE-----

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