source: http://www.securityfocus.com/bid/1660/info

A vulnerability exists in versions 4.x. x of AIX, from IBM. Any local user can utilize the -Z command to netstat, without needing to be root. This will cause interface statistics to be reset. This could potentially interfere with programs that track statistical information.

$ netstat -in --> shows stats
$ netstat -Zi --> clears them without checking the uid