I found a very interesting paper this evening whilst I was looking for details on listener security. The paper is not recent, written in 2003 but is still very current for most issues with the listener. The paper is in a newsletter written by Don Granaman whom I had contact with a few times when he was involved with the CIS Oracle benchmark. This is a great paper that details most of the known security issues known about for the Oracle listener. It starts on page seven of a newsletter in an article titled "Securing the Oracle Listener
". This is the title of the article on page 7 not the newsletter title. This is a very good article and well worth looking at.