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r1 - 2016-11-21 - 14:01:43 - HarlanStennYou are here: NTP >  Main Web > SecurityNotice > NtpBug3119
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-4.2.8p10 was released on 21 March 2017. It addresses 6 medium- and 5 low-severity security issues, 4 informational security topics, 15 bugfixes, and contains other improvements over 4.2.8p9.

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.

NTP Bug 3119

Mode 6 unauthenticated trap information disclosure and DDoS vector

  • Date Resolved: 21 Nov 2016
  • References: Sec 3118 / CVE-2016-9311 / VU#633847
  • Affects: ntp-4.0.90 (21 July 1999), possibly earlier, up to but not including ntp-4.2.8p9, and ntp-4.3.0 up to, but not including ntp-4.3.94.
  • CVSS2: MED 4.9 (AV:N/AC:H/Au:N/C:N/I:N/A:C)
  • CVSS3: MED 4.4 CVSS:3.0/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  • Summary: ntpd does not enable trap service by default. If trap service has been explicitly enabled, an attacker can send a specially crafted packet to cause a null pointer dereference that will crash ntpd, resulting in a denial of service.
  • Mitigation:
    • Implement BCP-38.
    • Use "restrict default noquery ..." in your ntp.conf file. Only allow mode 6 queries from trusted networks and hosts.
    • Upgrade to 4.2.8p9, or later, from the NTP Project Download Page or the NTP Public Services Project Download Page
    • Properly monitor your ntpd instances, and auto-restart ntpd (without -g) if it stops running.
  • Credit: This weakness was discovered by Matthew Van Gundy of Cisco.
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