topic How do you exclude and format unique specific fields from multivalued fields to be used in a subsearch? in Splunk Search

How do you exclude and format unique specific fields from multivalued fields to be used in a subsearch?

nickcardenas — Mon, 11 Feb 2019 20:29:49 GMT

Hello all,

I'm having some trouble formatting and dealing with multivalued fields.

My use case is as follows:

I have sourcetype-A that returns known malicious indicators (through multi-valued fields)
I have sourcetype-B that has DNS query logs from hosts
I'd like to make a search where I compile a list of "known malicious" domains from sourcetype-A, and in a subsearch (with soucetype-B being the main base search), compare all queries against the list created from the subsearch to see if a host queried a "malicious domain" (different index from sourcetype-A)

A sample log for sourcetype A looks like this:

                     Field                    Values
Event 1              indicator                x.xxx.x.xx
                                              hash
                                              someDomain.com
                                              http://DomainA.com
                                              supermalicious.com

Event 2              indicator                someDomain.com
                                              www.domainA.com
                                              someEmailAddress@domain.com
                                              http://helpmepls.com

When I use | eval indicator=mvfilter(match(indicator, "\.")) and |stats values(indicator), I receive somewhat of expected results (hashes are now gone and values are deduped across all events), but I still have the issue of having to exclude everything else that's not a domain or a URL.

I was thinking of using something like a URL parser app for Splunk to help with the formatting issues, but for that, I don't think I'm able to get by using |stats values(indicators)

Expected results:

someDomain.com
domainA.com
supermalicious.com
helpmepls.com

I'd appreciate if someone could point me in the correct direction or tell me if this is even possible through Splunk.

Thanks!

Re: How do you exclude and format unique specific fields from multivalued fields to be used in a subsearch?

woodcock — Tue, 12 Feb 2019 02:29:45 GMT

Like this:

| makeresults 
| eval raw="10.123.4.56,hash,someDomain.com,http://DomainA.com,supermalicious.com someDomain.com,www.domainA.com,someEmailAddress@domain.com,http://helpmepls.com" 
| makemv raw 
| mvexpand raw 
| rename raw AS _raw 
| rex max_match=0 "(?<indicator>[^,]+)" 

| rename COMMENT AS "Everything above generates sample event data; everything below is your solution"

| rex field=indicator mode=sed "s%^[^:/]+://%% s/^www\.//"
| eval indicator=mvfilter(match(indicator, "\.") AND NOT match(indicator, "(^\d+\.\d+\.\d+\.\d+$)|@"))
| eval indicator=lower(indicator)
| stats values(indicator)

Re: How do you exclude and format unique specific fields from multivalued fields to be used in a subsearch?

nickcardenas — Wed, 13 Feb 2019 15:16:46 GMT

Brilliant! This works as expected! I'll need to tinker with the regex to also omit IP addresses with specified ports such as123.123.123.2:8080 but once I add this, the provided answer will do exactly what I'm looking for.

Thank you so much!