NTP: Traffic amplification
Gentoo Linux Security Advisory
||GLSA 201401-08 /
||January 16, 2014
||January 16, 2014: 1
All supported architectures
NTP can be abused to amplify Denial of Service attack traffic.
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.
ntpd is susceptible to a reflected Denial of Service attack. Please
review the CVE identifiers and references below for details.
An unauthenticated remote attacker may conduct a distributed reflective
Denial of Service attack on another user via a vulnerable NTP server.
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.
All NTP users should upgrade to the latest version:
Code Listing 3.1: Resolution
# 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.