Hello, From what I saw about the ora-userenum.exe: 1) it is part of the Oracle Assessment Kit collection of tools for auditing oracle databases 2) it does not need credentials to connect to the db, hence the removal of select from all_users regarding public didn't do you any good 3) it is run as ora-userenum <host> <port> <sid> <userlistfile>. the last param is a file containing a list of users to check for their existence. Going through the source it is apparent that it initiates a login sequence to the db with each of those users and depending on some tns packet properties it receives back from the database server it deduces whether it is a valid username or not. You can have a copy of OAK (including source code) from http://www.databasesecurity.com/dbsec/OAK.zip. Basically there is nothing you can do about it at the db level other than to make sure that you don't give your users usernames that exist in this file :) . Best regards, ./ZQ