The symmetric-key feature in the receive function in ntp_proto.c in ntpd in NTP 3.x and 4.x before 4.2.8p2 performs state-variable updates upon receiving certain invalid packets, which makes it easier for man-in-the-middle attackers to cause a denial of service (synchronization loss) by spoofing the source IP address of a peer.
- http://www.kb.cert.org/vuls/id/374268
- http://www.oracle.com/technetwork/topics/security/bulletinapr2015-2511959.html
- http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
- https://kc.mcafee.com/corporate/index?page=content&id=SB10114
- https://github.com/ARPSyndicate/cve-scores