Default passwords of Oracle 11g?

It is possible to connect to the database without specifying a password. Once you've done that you can then reset the passwords. I'm assuming that you've installed the database on your machine; if not you'll first need to connect to the machine the database is running on.

1. Ensure your user account is a member of the dba group. How you do this depends on what OS you are running.
2. Enter sqlplus / as sysdba in a Command Prompt/shell/Terminal window as appropriate. This should log you in to the database as SYS.
3. Once you're logged in, you can then enter
   

   alter user SYS identified by "newpassword";
   

   to reset the SYS password, and similarly for SYSTEM.

See also here.
(Note: I haven't tried any of this on Oracle 11g; I'm assuming they haven't changed things since Oracle 10g.)

http://stackoverflow.com/questions/740119/default-passwords-of-oracle-11g