[asterisk-biz] Hacker's attack on Asterisk by thses addresses "66.7.197.76" and "200.90.72.141"

Hi   IMy asterisk has been hacked my this IP "66.7.197.76". When i blocked this ip from Linux Firewall then he tried to attack from 2nd IP "200.90.72.141". He  fhound one my extension with a weak password and started dialing out. Thanks   Faiz