Hi,
PowerShell script to validate that all machines in your OU have Symantec Endpoint Protection (SEP) anti-virus client installed and started. Generates a color-coded Excel report highlighting problematic nodes.
Refer this link and download the script from here: http://gallery.technet.microsoft.com/scriptcenter/Symantec-Endpoint-8e47c450
Reference link: http://www.reddit.com/r/sysadmin/comments/25mtye/finding_symantec_endpoint_clients_on_network/
Note: This method is not supported by Symantec. Symantec recommends to use unmanaged detector.
Script may need to be modified for 12.1 clients