A SIMPLE SOLUTION FOR ORACLE LISTENER REMOTE VERSION DISCLOSURE
At this note I will give you some brief information about how you can hide Oracle listener version information from hackers and network scanning tools. This vulnerability is called tns remote version disclosure.
First we know that ; there is no parameters at Oracle listeners to hide version information.
And the legal solution for this problem is to filter network traffic by any means. But this solution can be very expensive to hide version information, If you think about you have many listeners.
Therefore the simple solution is to change the default listener configuration.
The main point is that ; hackers assume that you are using factory setting at your database listener. At the factory settings the name of the listener is LISTENER and the default port is 1521 or 1522
Now ; After installing Oracle binary if you do not change default listener parameters. Hackers can get your installed binary version name by sending version command to 1521 port. The output will be liket that.
After getting this information; Hackers will try the known vulnerabilities to hack your database . Therefore it is important to hide Oracle binary version.
You can do it very easily way. Change default listener name to any complicated name. Like on the following picture.
And then restart the listener.
After that ; when any scanning tools or hackers attempt to find Oracle binary version. They will get the below answers.
After changing Listener Name, if you change default port. It will be much more difficult for hackers to hack Oracle listener. But do not forget that changing listener port could be difficult job.
I will work on listener security topics on the next notes.