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Gentoo Linux Security Advisory GLSA 201401-08
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http://security.gentoo.org/
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Severity: Normal
Title: NTP: Traffic amplification
Date: January 16, 2014
Bugs: #496776
ID: 201401-08

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Synopsis
========

NTP can be abused to amplify Denial of Service attack traffic.

Background
==========

NTP is a protocol designed to synchronize the clocks of computers over
a network. The net-misc/ntp package contains the official reference
implementation by the NTP Project.

Affected packages
=================

-------------------------------------------------------------------
Package / Vulnerable / Unaffected
-------------------------------------------------------------------
1 net-misc/ntp < 4.2.6_p5-r10 >= 4.2.6_p5-r10

Description
===========

ntpd is susceptible to a reflected Denial of Service attack. Please
review the CVE identifiers and references below for details.

Impact
======

An unauthenticated remote attacker may conduct a distributed reflective
Denial of Service attack on another user via a vulnerable NTP server.

Workaround
==========

We modified the default ntp configuration in =net-misc/ntp-4.2.6_p5-r10
and added "noquery" to the default restriction which disallows anyone
to query the ntpd status, including "monlist".

If you use a non-default configuration, and provide a ntp service to
untrusted networks, we highly recommend you to revise your
configuration to disable mode 6 and 7 queries for any untrusted
(public) network.

You can always enable these queries for specific trusted networks. For
more details please see the "Access Control Support" chapter in the
ntp.conf(5) man page.

Resolution
==========

All NTP users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/ntp-4.2.6_p5-r10"

Note that the updated package contains a modified default configuration
only. You may need to modify your configuration further.

References
==========

[ 1 ] CVE-2013-5211
http://nvd.nist.gov/nvd.cfm?cvename=CVE-2013-5211
[ 2 ] VU#348126
http://www.kb.cert.org/vuls/id/348126

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

http://security.gentoo.org/glsa/glsa-201401-08.xml

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users' machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
https://bugs.gentoo.org.

License
=======

Copyright 2014 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/2.5