Hunting: Internal DNS Logs using ArcSight Logger

If you have read the latest Mandiant M-Trends 2012: An Evolving Threat report you might have noticed on page 10 this statement:

The ZIP archive contained several benign files and an executable disguised as a PDF document via a modified resources section. When executed, the malware beaconed to a domain that contained the organization’s specific name as the third level of the address (such as “victimA.youareowned.com”).

Then later in the report the Mandiant Folks call out the need for having your internal DNS logs as a way to combat these type of attacks. This got me thinking of how I could go hunting through my organizations internal DNS logs. Thankfully, we have these logs and they are  being forwarded to an ArcSight Logger so for this post I am going to leverage Logger for searching internal dns logs.

Let’s assume for this exercise your organization name is LMN Widget Maker Inc and you are customarily known as lmnwidgets and in the Mandiant example above the malware would have beaconed to lmnwidgets.youareowned.com.

For this exercise I am using BIND DNS for the logs so your queries might have to change for Microsoft DNS but you should get the idea. For the sake of it as well I will show the results with a limited field set so you only see the important data for this exercise.

You will need to search query events and you will want to exclude queries for your organizations domain lmnwidgets.com. From there you will have to leverage the capabilities of ArcSight and do a CONTAINS operator in the search for lmnwidgets. Your search filter would look something like this:

Logger Search for lmnwidget

And for those of you used to creating filters in ESM it would look like this:

LMNWidget Search ESM

This hopefully would not result in any events but in this exercise it did.

LMNWIDGET Search Results

Now that you have found you have some interesting results from your searches you can dig a little deeper and take it from there.

Happy Hunting!!!!