Error Codes as a means for Information Gathering

Our next step is called Analysis of Error Codes.  In this stage, we are using common responses to certain errors as a way to get information.   One common error that pretty much all internet users has ran into at least once is the HTTP 404 error.

Example, if someone goes to the following url:  http://r.martint.net/asdads.html - they will be greeted with:

Not FoundThe requested URL /asdads.html was not found on this server.Apache/2.2.3 (CentOS) Server at r.martint.net Port 80

So, this error tells me the page is hosted on a Apache web server on port 80 running CentOS (Linux Variant).

Wen servers are not the only type of servers affected by this - people often use common errors from databases for penetration testing.  Some database errors can give us the IP Address of the database server, and then we try SQL injection to fool the server into authenticating our request.

Analysis of Error codes ends our discussion on Information gathering and now it is time to move on to configuration management testing.  More on this will be posted in the next post.