NTP Bug 2939

reslist NULL pointer dereference

  • Date Resolved: Stable (4.2.8p6) 19 Jan 2016; Dev (4.3.90) 19 Jan 2016
  • References: Sec 2939 / CVE-2015-7977
  • Affects: All ntp-4 releases up to, but not including 4.2.8p6, and 4.3.0 up to, but not including 4.3.90
  • CVSS: (AV:N/AC:M/Au:N/C:N/I:N/A:P) Base Score: 4.3
  • Summary: An unauthenticated ntpdc reslist command can cause a segmentation fault in ntpd by causing a NULL pointer dereference.
  • Mitigation:
    • Implement BCP-38.
    • Upgrade to 4.2.8p6, or later, from the NTP Project Download Page or the NTP Public Services Project Download Page.
    • If you are unable to upgrade:
      • 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 Stephen Gray <> of Cisco ASIG.

This topic: Main > SecurityNotice > NtpBug2939
Topic revision: r1 - 2016-01-20 - 11:35:10 - HarlanStenn
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