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-4.2.8p15 was released on 23 June 2020. It addresses 1 medium-severity security issue in ntpd, and provides 13 non-security bugfixes over 4.2.8p13.

Please see the NTP Security Notice for vulnerability and mitigation details.

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NTP Bug 3011

Duplicate IPs on unconfig directives will cause an assertion botch in ntpd

• Date Resolved: Stable (4.2.8p7) 26 Apr 2016; Dev (4.3.92) 26 Apr 2016
• References: Sec 3011 / CVE-2016-2516 / VU#718152
• Affects: All ntp-4 releases up to, but not including 4.2.8p7, and 4.3.0 up to, but not including 4.3.92
• CVSS2: MED 6.3 (AV:N/AC:M/Au:S/C:N/I:N/A:C)
• CVSS3: MED 4.2 (CVSS:3.0/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:H)
• Summary: If ntpd was expressly configured to allow for remote configuration, a malicious user who knows the controlkey for ntpq or the requestkey for ntpdc (if mode7 is expressly enabled) can create a session with ntpd and if an existing association is unconfigured using the same IP twice on the unconfig directive line, ntpd will abort.
• Mitigation:
  • Implement BCP-38.
  • Upgrade to 4.2.8p7, or later, from the NTP Project Download Page or the NTP Public Services Project Download Page
  • Properly monitor your ntpd instances
• Credit: This weakness was discovered by Yihan Lian of the Cloud Security Team, Qihoo 360.