The ORA-28009 error is a new error for Oracle 9i. Beginning with Oracle 9i, when you sign on as SYS, you must sign on with SYSDBA privileges. In SQL*Plus, you do that as follows:
sqlplus /nolog connect sys as sysdba
Beginning with Oracle 9i, you cannot sign on to the SYS account without also specifying the SYSDBA privilege. Failure to do so results in the ORA-28009 error. Sign on appropriately, and you should have no problems with the SYS account.
This was first published in September 2004