NTP users are strongly urged to take immediate action to ensure that their NTP daemons are not susceptible to being used in distributed denial-of-service (DDoS) attacks. Please also take this opportunity to defeat denial-of-service attacks by implementing Ingress and Egress filtering through BCP38.
ntp-4.2.8p9was released on 21 November 2016. It addresses 1 high- (Windows only), 2 medum-, 2 medum-/low-, and 5 low-severity security issues, 28 bugfixes, and contains other improvements over 4.2.8p8.
Please see the NTP Security Notice for vulnerability and mitigation details.Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.
ntpqprotocol is vulnerable to replay attacks. The sequence number being included under the signature fails to prevent replay attacks for two reasons. Commands that don't require authentication can be used to move the sequence number forward, and NTP doesn't actually care what sequence number is used so a packet can be replayed at any time. If, for example, an attacker can intercept authenticated reconfiguration commands that would. for example, tell
ntpdto connect with a server that turns out to be malicious and a subsequent reconfiguration directive removed that malicious server, the attacker could replay the configuration command to re-establish an association to malicious server. Yes, this is an unlikely scenario, but it could still happen.
ntpdto get time from multiple sources.
restrictstatments in your
ntp.conffile to limit who is allowed to issue
ntpqqueries and remote configuration commands.