http://support.ntp.org/bin/view/Main/SecurityNoticeNTF's NTP Project has been notified of a number of vulnerabilities from Neel Mehta and Stephen Roettger of Google's Security Team.
The two most serious of these issues and four less serious issues have been resolved as of ntp-4.2.8, which was released on 18 December 2014.
There are still two less significant issues to be addressed. We're expecting to fix these within the next month.
https://rhn.redhat.com/errata/RHSA-2014-2024.htmlMultiple buffer overflow flaws were discovered in ntpd's crypto_recv(),
ctl_putdata(), and configure() functions. A remote attacker could use
either of these flaws to send a specially crafted request packet that could
crash ntpd or, potentially, execute arbitrary code with the privileges of
the ntp user. Note: the crypto_recv() flaw requires non-default
configurations to be active, while the ctl_putdata() flaw, by default, can
only be exploited via local attackers, and the configure() flaw requires
additional authentication to exploit. (CVE-2014-9295)
It was found that ntpd automatically generated weak keys for its internal
use if no ntpdc request authentication key was specified in the ntp.conf
configuration file. A remote attacker able to match the configured IP
restrictions could guess the generated key, and possibly use it to send
ntpdc query or configuration requests. (CVE-2014-9293)
It was found that ntp-keygen used a weak method for generating MD5 keys.
This could possibly allow an attacker to guess generated MD5 keys that
could then be used to spoof an NTP client or server. Note: it is
recommended to regenerate any MD5 keys that had explicitly been generated
with ntp-keygen; the default installation does not contain such keys).
A missing return statement in the receive() function could potentially
allow a remote attacker to bypass NTP's authentication mechanism.