Programmatically filter unusual DNS Requests with Cisco Umbrella APIs
We use the Web in our on a regular basis lives to get work executed, handle our lives, and even socialize. We take this Web utilization with no consideration nowadays, however the actuality is that we’re speaking greater than ever on a world scale, instantaneously, and infrequently, with people we’ve by no means met in-person or with third-party companies we don’t absolutely perceive.
From a cybersecurity perspective, this appears to be like like numerous DNS site visitors to have to observe, perceive, and examine. And, there are growing causes to just do that. After the most important 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, partially, requested them to higher perceive their DNS site visitors.
In fact, pipelines are usually not the one targets of such assaults, that means we want cheap methodologies for figuring out and investigating doubtlessly malicious domains. On this article, we stroll you thru the way you would possibly programmatically acquire visibility into and examine unusual DNS requests utilizing Cisco Umbrella APIs.
Preliminary developer setup
To create this automation, we assume you’ve an lively Cisco Umbrella account with API entry, Python3, and an built-in developer surroundings (IDE) that helps Python.
Should you’re not but an Umbrella person, otherwise you’d merely prefer to create a proof-of-concept (POC) round this, you may leverage the always-on Umbrella Safe Web Gateway sandbox via 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 large quantity of site visitors processing and evaluation, Umbrella maintains an updated “Prime 1-Million Domains” checklist as a CSV. This data establishes a baseline of what site visitors is frequent.
We are able to decide what site visitors coming out of your Umbrella community is rare by evaluating it to this Prime 1-Million Domains checklist.
To do that, we make an API name utilizing the Umbrella Stories API to retrieve the Prime Locations seen by your Umbrella community up to now week. The decision returns a listing of domains from most to least frequent, one per row, as a CSV, that we will 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 received’t match an Umbrella Prime 1-Million area)
We are able to then write logic that compares the domains seen by your community to Umbrella’s Prime 1-Million and provides any of your domains that aren’t on that checklist to a brand new CSV.
Pattern Code
We’ve written a pattern Python script that can assist you obtain this utilizing your personal DNS site visitors! That script, together with directions for working it, may be discovered right here.
Investigating unusual domains with Umbrella APIs
When you’ve recognized which domains seen by your community are thought-about much less frequent, you could select to additional examine some—or all—of them utilizing Umbrella Examine.
When you have an Umbrella DNS Safety Benefit or Safe Web Gateway (SIG) package deal, within the Umbrella dashboard, you may navigate to Examine > Sensible Search and seek for the area you’d like to analyze. 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 are able to see that this area is assessed as malware and is already on a Malware Block Checklist; although, if we wished to, we may discover extra data on this area throughout Talos, Google, or VirusTotal (prime proper).
Determine 2: The chance rating and safety indicators for examplemalwaredomain.com
Scrolling down the outcomes, we subsequent see the chance rating assigned to this area and the safety indicators that went into calculating that rating. On this case, the area is assessed as Excessive Threat, with extra data on the safety indicators used right here.
After viewing primary data on the area, equivalent 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 report data on the area (see under). You’ll discover that Umbrella Examine lets you additional examine the related e-mail deal with and nameservers.
Determine 3: WHOIS report information for examplemalwaredomain.com
Lastly, we will view a world map exhibiting 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, that means that the investigation of those unusual domains can be executed programmatically.
Extra alternatives for automation
What are the probabilities 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 data and any menace 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 Modifications – use the Umbrella Locations Checklist API to permit or block a number of of the unusual domains
- Reporting – export the unusual domains, and maybe data on them from Umbrella Examine, right into a extra palatable format like PDF. Area data is also 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 may orchestration an automation workflow with a number of steps (not all of these steps want be automated) utilizing Cisco XDR. The workflow would possibly embody all steps your group requires for investigation and incident response.
- Communication – relatively than save the ensuing CSV of domains regionally, you could select to robotically e-mail the outcomes to events or put up the outcomes to a messaging platform like WebEx.
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