r1 - 2015-10-23 - 09:05:30 - HarlanStennYou are here: NTP >  Main Web > SecurityNotice > NtpBug2902
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 medum- 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 2902

Configuration directives to change "pidfile" and "driftfile" should only be allowed locally.

  • Date Resolved: Stable (4.2.8p4) 21 Oct 2015
  • References: Sec 2902 / CVE-2015-5196
  • 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:C/A:C) Base Score: 6.2 worst case
  • Summary: If ntpd is configured to allow for remote configuration, and if the (possibly spoofed) source IP address is allowed to send remote configuration requests, and if the attacker knows the remote configuration password, it's possible for an attacker to use the "pidfile" or "driftfile" directives to potentially overwrite other files.
  • 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 cannot upgrade, don't enable remote configuration.
    • If you must enable remote configuration and cannot upgrade, remote configuration of NTF's ntpd requires:
      • an explicitly configured trustedkey, and you should also configure a controlkey.
      • access from a permitted IP. You choose the IPs.
      • authentication. Don't disable it. Practice secure key safety.
    • Monitor your ntpd instances.
  • Credit: This weakness was discovered by Miroslav Lichvar of Red Hat.
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