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r1 - 2017-03-22 - 01:41:39 - HarlanStennYou are here: NTP >  Main Web > SecurityNotice > NtpBug3376
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 3379

NTP-01-004 NTP: Potential Overflows in ctl_put() functions (Medium)

  • Date Resolved: 21 Mar 2017
  • References: Sec 3379 / CVE-2017-6458 / VU#325339
  • Affects: All versions of NTP, up to but not including ntp-4.2.8p10, and ntp-4.3.0 up to, but not including ntp-4.3.94.
  • CVSS2: MED 4.6 (AV:N/AC:H/Au:M/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: ntpd makes use of different wrappers around ctl_putdata() to create name/value ntpq (mode 6) response strings. For example, ctl_putstr() is usually used to send string data (variable names or string data). The formatting code was missing a length check for variable names. If somebody explicitly created any unusually long variable names in ntpd (longer than 200-512 bytes, depending on the type of variable), then if any of these variables are added to the response list it would overflow a buffer.
  • Mitigation:
    • Implement BCP-38.
    • Upgrade to 4.2.8p10, or later, from the NTP Project Download Page or the NTP Public Services Project Download Page
    • If you don't want to upgrade, then don't setvar variable names longer than 200-512 bytes in your ntp.conf file.
    • Properly monitor your ntpd instances, and auto-restart ntpd (without -g) if it stops running.
  • Credit: This weakness was discovered by Cure53.
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