SynopsisThe remote CentOS host is missing one or more security updates.
DescriptionUpdated ntp packages that fix two security issues are now available for Red Hat Enterprise Linux 6 and 7.
Red Hat Product Security has rated this update as having Important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.
The Network Time Protocol (NTP) is used to synchronize a computer's time with a referenced time source.
It was discovered that ntpd as a client did not correctly check timestamps in Kiss-of-Death packets. A remote attacker could use this flaw to send a crafted Kiss-of-Death packet to an ntpd client that would increase the client's polling interval value, and effectively disable synchronization with the server. (CVE-2015-7704)
It was found that ntpd did not correctly implement the threshold limitation for the '-g' option, which is used to set the time without any restrictions. A man-in-the-middle attacker able to intercept NTP traffic between a connecting client and an NTP server could use this flaw to force that client to make multiple steps larger than the panic threshold, effectively changing the time to an arbitrary value.
Red Hat would like to thank Aanchal Malhotra, Isaac E. Cohen, and Sharon Goldberg of Boston University for reporting these issues.
All ntp users are advised to upgrade to these updated packages, which contain backported patches to resolve these issues. After installing the update, the ntpd daemon will restart automatically.
SolutionUpdate the affected ntp packages.