Navigating the 'C' of Network Discovery

10:12 AM -- One of the things I often hear from clients is "I don’t know what my network looks like." Worse yet, I’ve heard a lot of consultants and otherwise very smart people tell me that they don’t even know where to start looking at an enterprise network. True, finding every nook and cranny of an organization might be beyond the scope of most mortals -- but there are lots of tools and techniques to expedite the process.

Let’s start with good old fashioned phone calls. Calling every network operations guy who works for the company -- or has ever provisioned a new domain -- will probably give you a comprehensive list of all the stupid domains that have been created, acquired, or otherwise ended up in your organization's possession. It might sound painful, but it really is the best way to get started, assuming it’s not a blackbox assessment.

Next, look at your favorite search engines to find anything you can about the network. Get and send some emails to see if you can learn anything about naming conventions or IP space. Look at Alexa for the company’s name and see if you can find any other "cnames" (such as webmail.company.com and marketing.company.com).

Now we come to my favorite piece of the puzzle. Use tools like fierce to do DNS enumeration. Building custom dictionary files for a company can help you find all kinds of interesting spots in the organization.

Next, use tools like My IP Neighbors on each IP you find. This will help you see what other domains might be residing on the same box. Just because your Website is secure doesn’t mean the other Website on the same host is, too.

Then start scanning the Class C addresses around the network. See what else is there. Did you know your organization runs a marketing site on some unpatched Win2k server sitting under some guy’s desk to do giveaways? Well, there it is, in your network -- you should probably audit it.

That mobile app that has an API to your backend systems -- but doesn’t log? Yup, that’s probably a good thing to audit too.

Figuring out your network is the only way to begin an audit. If you aren’t paying attention to the rest of your network and you are only focusing on the front door, chances are you are already owned -- you just don’t know it yet. Let’s just hope the bad guys don’t figure out what they have before you do.

– RSnake is a red-blooded lumberjack whose rants can also be found at Ha.ckers and F*the.net. Special to Dark Reading