Hi, I didn't tried yet, but common sense says it will work.
CREATE TRIGGER SYS.LOGON_muhammed AFTER LOGON ON SYS.SCHEMA /
Once of this day I will have to fix several pending security items I have on my database I discovered recently, like the fact you can capture with a network monitor the command enabling the role and the password.
Now I have to develop and certify on java, not to work in database. :) -- //www.freelists.org/webpage/oracle-l