Hacker's first attempt in many cases is to retrieve SID information from the database server as this information is used in conducting different attacks. The Oracle System ID is used to uniquely identify a particular database on a system. Up to Oracle 9i R2 SID information could easily be retrieved by intruder but since the release of 10g Oracle tried to hide this information. One of the methods adapted by hackers is to try different combinations of oracle database SID names and see if it matches the SID name on the database server.