If no rows returned, you don't appear to be suffering from this 'feature'. If rows are returned and you aren't expecting to (or don't) pay for Advanced Security Option, please let me know the results!
select osuser, count(*) from v$session_connect_info where upper(network_service_banner) like '%MD5%' group by osuser;
Status information for Oracle Advanced Security is available after the connection has been established. The information is contained in the RDBMS virtual table v$session_connect_info
select * from v$version;