Programmatically filter unusual DNS Requests with Cisco Umbrella APIs

We use the Web in our on a regular basis lives to get work accomplished, handle our lives, and even socialize. We take this Web utilization without any consideration today, however the actuality is that we’re speaking greater than ever on a world scale, instantaneously, and sometimes, with of us we’ve by no means met in-person or with third-party providers we don’t totally perceive.

From a cybersecurity perspective, this seems to be like loads of DNS site visitors to have to observe, perceive, and examine. And, there are rising causes to just do that. After the foremost Colonial Pipeline ransomware assault that resulted in a $4.4 million ransom fee in 2021, the TSA issued (and has since, reissued) a safety directive to pipeline utility corporations that, partly, requested them to higher perceive their DNS site visitors.

In fact, pipelines should not the one targets of such assaults, which means we want cheap methodologies for figuring out and investigating probably malicious domains. On this article, we stroll you thru the way you may programmatically achieve visibility into and examine unusual DNS requests utilizing Cisco Umbrella APIs.

Preliminary developer setup

To create this automation, we assume you’ve got an lively Cisco Umbrella account with API entry, Python3, and an built-in developer setting (IDE) that helps Python.

Should you’re not but an Umbrella person, otherwise you’d merely wish to create a proof-of-concept (POC) round this, you possibly can leverage the always-on Umbrella Safe Web Gateway sandbox by means of Cisco DevNet.

Defining what site visitors is “unusual”

The day earlier than writing this text, Cisco Umbrella processed over 800 billion DNS requests. Because of this persistently huge quantity of site visitors processing and evaluation, Umbrella maintains an updated “High 1-Million Domains” listing as a CSV. This data establishes a baseline of what site visitors is widespread.

We will decide what site visitors coming out of your Umbrella community is rare by evaluating it to this High 1-Million Domains listing.

To do that, we make an API name utilizing the Umbrella Stories API to retrieve the High Locations seen by your Umbrella community prior to now week. The decision returns an inventory of domains from most to least widespread, one per row, as a CSV, that we are able to clear to take away the rank order and non-domains. (For instance, take away the 8 on this row: 8,www.google.com, and take away IP deal with locations as a result of they gained’t match an Umbrella High 1-Million area)

We will then write logic that compares the domains seen by your community to Umbrella’s High 1-Million and provides any of your domains that aren’t on that listing to a brand new CSV.

Pattern Code

We’ve written a pattern Python script that will help you obtain this utilizing your individual DNS site visitors! That script, together with directions for operating it, might be discovered right here.

Investigating unusual domains with Umbrella APIs

When you’ve recognized which domains seen by your community are thought of much less widespread, you could select to additional examine some—or all—of them utilizing Umbrella Examine.

If in case you have an Umbrella DNS Safety Benefit or Safe Web Gateway (SIG) package deal, within the Umbrella dashboard, you possibly can navigate to Examine > Sensible Search and seek for the area you’d like to research. You’ll see outcomes that present data wanting one thing like what you see under for examplemalwaredomain.com:

Determine 1: The start of Umbrella Examine outcomes for examplemalwaredomain.com

The outcomes first present you each the content material and safety classes for the area, offered by Cisco Talos. We will see that this area is classed as malware and is already on a Malware Block Checklist; although, if we needed to, we may discover further data on this area throughout Talos, Google, or VirusTotal (high proper).

Determine 2: The chance rating and safety indicators for examplemalwaredomain.com

Scrolling down the outcomes, we subsequent see the danger rating assigned to this area and the safety indicators that went into calculating that rating. On this case, the area is classed as Excessive Danger, with further data on the safety indicators used right here.

After viewing primary data on the area, corresponding to when it was created and from what nation it originates, in addition to related observables like IP addresses, identify servers, and recordsdata, you’ll discover WHOIS file data on the area (see under). You’ll discover that Umbrella Examine permits you to additional examine the related electronic mail deal with and nameservers.

Determine 3: WHOIS file information for examplemalwaredomain.com

Lastly, we are able to view a world map displaying the place DNS requests to examplemalwaredomain.com. Within the instance map under, over 95% of DNS requests to this area originate from america.

Determine 4: International requestor distribution map for examplemalwaredomain.com

These Umbrella Examine outcomes are additionally accessible as a part of the Umbrella Examine API, which means that the investigation of those unusual domains will also be accomplished programmatically.

Extra alternatives for automation

What are the chances for constructing upon the automation we’ve offered within the pattern code?

• Examine – including logic that for every unusual area, an API name is made to the Umbrella Examine endpoint to retrieve information and any risk intel
• Ticketing – you would combine a ticketing system, like Jira, by leveraging its API to create and assign a ticket for every unusual area
• Coverage Adjustments – use the Umbrella Locations Checklist API to permit or block a number of of the unusual domains
• Reporting – export the unusual domains, and maybe information on them from Umbrella Examine, right into a extra palatable format like PDF. Area information may be enhanced by intel from different safety merchandise, by viewing related gadgets and their relationships with the area utilizing JupiterOne, and/or utilized in a visualization.
• Orchestration – you possibly can orchestration an automation workflow with a number of steps (not all of these steps want be automated) utilizing Cisco XDR. The workflow may embody all steps your group requires for investigation and incident response.
• Communication – moderately than save the ensuing CSV of domains regionally, you could select to routinely electronic mail the outcomes to events or publish the outcomes to a messaging platform like WebEx.

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