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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Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.

NTP Bug 2913

TALOS-CAN-0052: mode 7 loop counter underrun

• Date Resolved: Stable (4.2.8p4) 21 Oct 2015
• References: Sec 2913 / CVE-2015-7848
• Affects: All ntp-4 releases up to, but not including 4.2.8p4, and 4.3.0 up to, but not including 4.3.77
• CVSS: (AV:N/AC:H/Au:M/C:N/I:N/A:C) Base Score: 4.6
• Summary: If ntpd is configured to enable mode 7 packets, and if the use of mode 7 packets is not properly protected thru the use of the available mode 7 authentication and restriction mechanisms, and if the (possibly spoofed) source IP address is allowed to send mode 7 queries, then an attacker can send a crafted packet to ntpd that will cause it to crash.
• Mitigation:
  • Implement BCP-38.
  • Upgrade to 4.2.8p4, or later, from the NTP Project Download Page or the NTP Public Services Project Download Page.
  • If you are unable to upgrade:
    • In ntp-4.2.8, mode 7 is disabled by default. Don't enable it.
    • If you must enable mode 7:
      • configure the use of a requestkey to control who can issue mode 7 requests.
      • configure restrict noquery to further limit mode 7 requests to trusted sources.
  • Monitor your ntpd instances.
• Credit: This weakness was discovered by Aleksandar Nikolic of Cisco Talos.