The config_auth function in ntpd in NTP before 4.2.7p11, when an auth key is not configured, improperly generates a key, which makes it easier for remote attackers to defeat cryptographic protection mechanisms via a brute-force attack.
https://www.arista.com/en/support/advisories-notices/security-advisories/1047-security-advisory-8
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20141222-ntpd
https://kc.mcafee.com/corporate/index?page=content&id=SB10103
https://h20564.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c04916783
https://h20564.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c04790232
https://bugzilla.redhat.com/show_bug.cgi?id=1176032
http://www.securityfocus.com/bid/71757
http://www.oracle.com/technetwork/security-advisory/cpuoct2016-2881722.html
http://www.mandriva.com/security/advisories?name=MDVSA-2015:003
http://www.kb.cert.org/vuls/id/852879
http://support.ntp.org/bin/view/Main/SecurityNotice
http://secunia.com/advisories/62209
http://rhn.redhat.com/errata/RHSA-2015-0104.html
http://rhn.redhat.com/errata/RHSA-2014-2025.html
http://marc.info/?l=bugtraq&m=144182594518755&w=2
http://marc.info/?l=bugtraq&m=142853370924302&w=2
http://marc.info/?l=bugtraq&m=142590659431171&w=2
http://marc.info/?l=bugtraq&m=142469153211996&w=2