Detecting Dynamic DNS Domains in Splunk

Posted on August 8th, 2015 in New Domains by dglosser

From http://blogs.splunk.com/2015/08/04/detecting-dynamic-dns-domains-in-splunk:

Name a security breach or sample of malware in the last five years and you will come across a fairly common denominator: the malware (or the method of data exfiltration) used a “Dynamic DNS” hostname to connect to the Internet….

The use of dynamic DNS providers for malicious purposes is extremely wide spread. OpenDNS Security Labs reported that over 56% of subdomains on some DDNS providers were malicious.  Similarly, Cisco reported that dynamic DNS linked websites were 19% more likely to be malicious than other websites. The question is not “does the threat exist?” but rather, how does a defender detect these domains or mitigate them?

One idea is to create a lookup table by using a great blog post by OpenDNS from 2015 that discusses the top 20 most malicious dynamic DNS providers. Another option is downloading all known dynamic DNS providers (provided by www.malware-domains.com). This list is much more comprehensive than the “top 20”, but it may increase your false positives as it is a substantially larger list. This zip requires some modifications to turn into a lookup table, but you can find scripts on github to help you automate the process…….

Please let us know of any Dynamic DNS Domains not on the list and we’ll add them.


Comments are closed.