AIX 5.3 TL 9 : xntpd (IZ71093)
Medium Nessus Plugin ID 63801
SynopsisThe remote AIX host is missing a security patch.
Description'NTP mode 7 (MODE_PRIVATE) is used by the ntpdc query and control utility. In contrast, ntpq uses NTP mode 6 (MODE_CONTROL), while routine NTP time transfers use modes 1 through 5. Upon receipt of an incorrect mode 7 request or a mode 7 error response from an address that is not listed in a 'restrict ... noquery' or 'restrict ...
ignore' segment, ntpd will reply with a mode 7 error response and log a message.'
'If an attacker spoofs the source address of ntpd host A in a mode 7 response packet sent to ntpd host B, both A and B will continuously send each other error responses, for as long as those packets get through.'
'If an attacker spoofs an address of ntpd host A in a mode 7 response packet sent to ntpd host A, then host A will respond to itself endlessly, consuming CPU and logging excessively.'.
SolutionInstall the appropriate interim fix.