[ GLSA 201401-08 ] NTP: Traffic amplification

[GLSA]

Gentoo Linux Security Advisory

Title: NTP: Traffic amplification (GLSA 201401-08)
Severity: normal
Exploitable: remote
Date: January 16, 2014
Bug(s): #496776
ID: 201401-08

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: net-misc/ntp
Vulnerable: < 4.2.6_p5-r10
Unaffected: >= 4.2.6_p5-r10
Architectures: All supported architectures


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: