NTP ntpd Mode 7 Error Response Packet Loop Remote DoS
Medium Nessus Plugin ID 43156
SynopsisThe remote network time service has a denial of service vulnerability.
DescriptionThe version of ntpd running on the remote host has a denial of service vulnerability. It responds to mode 7 error packets with its own mode 7 error packets. A remote attacker could exploit this by sending a mode 7 error response with a spoofed IP header, setting the source and destination IP addresses to the IP address of the target. This would cause ntpd to respond to itself endlessly, consuming excessive amounts of CPU, resulting in a denial of service.
SolutionUpgrade to NTP 4.2.4p8 / 4.2.6 or later.