Make sure that you take all relevant security precautions for your Oracle database.
For more information on Oracle database security with your SAP system, see the following security docmentation:
Oracle Under UNIX
Oracle Under Windows
You also need to take security precautions at operating system level. For more information, see:
SAP documentation on operating system security with the SAP system:
SAP System Security Under UNIX/LINUX
SAP System Security Under Windows
The documentation provided by your operating system vendor