Debu has an interesting pointer to an Oracle security paper
The paper is not bad but I am concerned about the sentence "It is a good idea to create a separate schema, such as Sec_Manager, without any privileges—not even CONNECT" that seems to indicate that the author is used to simply granting the CONNECT role rather than the system privilege CREATE SESSION to allow a user to access the database. he goes on to say later that "Even if an intruder with the DBA privilege were to grant the CONNECT privilege to the security objects holder" in order for the intruder to connect as the security package owner and to then read the security authentication packages contents (These were wrapped to prevent this). This indicates a lack of detailed knowledge as again he assumes that CONNECT is a privilege and not a role and that it is necessary to access the database. He also says that an intruder with DBA would grant CONNECT to the security schema owner so that it can be connected as. This would be unnecessary in order to view package contents as they are available via DBA_SOURCE. Maybe the author is limited by trying to get the point across but it does seem like a better explanation of roles and privileges and even access to read package source is needed.