Run the Intelligent Updater:
http://www.symantec.com/security_response/definitions/download/detail.jsp?gid=sep
Updates for NTP and PTP can be downloaded as well.
http://www.symantec.com/security_response/definitions/download/detail.jsp?gid=ips
http://www.symantec.com/security_response/definitions/download/detail.jsp?gid=sonar