r1 - 2017-03-22 - 01:40:02 - HarlanStennYou are here: NTP >  Main Web > SecurityNotice > NtpBug3377
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 3377

NTP-01-002 NTP: Buffer Overflow in ntpq when fetching reslist from a malicious ntpd (Medium)

  • Date Resolved: 21 Mar 2017
  • References: Sec 3377 / CVE-2017-6460 / VU#325339
  • Affects: All versions of ntpq, 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 4.9 (AV:N/AC:H/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: A stack buffer overflow in ntpq can be triggered by a malicious ntpd server when ntpq requests the restriction list from the server. This is due to a missing length check in the reslist() function. It occurs whenever the function parses the serverís response and encounters a flagstr variable of an excessive length. The string will be copied into a fixed-size buffer, leading to an overflow on the functionís stack-frame. Note well that this problem requires a malicious server, and affects ntpq, not ntpd.
  • Mitigation:
    • Upgrade to 4.2.8p10, or later, from the NTP Project Download Page or the NTP Public Services Project Download Page
    • If you can't upgrade your version of ntpq then if you want to know the reslist of an instance of ntpd that you do not control, know that if the target ntpd is malicious that it can send back a response that intends to crash your ntpq process.
  • Credit: This weakness was discovered by Cure53.
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