The search takes the DNS records and their answers results of the discovered_dns_records lookup and finds if any records have changed by searching DNS response from the Network_Resolution datamodel across the last day.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Network_Resolution
- Last Updated: 2020-07-21
- Author: Jose Hernandez, Splunk
- ID: 44d3a43e-dcd5-49f7-8356-5209bb369065
|T1071.004||DNS||Command And Control|
Kill Chain Phase
- Command & Control
- CIS 1
- CIS 3
- CIS 8
- CIS 12
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | inputlookup discovered_dns_records | rename answer as discovered_answer | join domain[ |tstats `security_content_summariesonly` count values(DNS.record_type) as type, values(DNS.answer) as current_answer values(DNS.src) as src from datamodel=Network_Resolution where DNS.message_type=RESPONSE DNS.answer!="unknown" DNS.answer!="" by DNS.query | rename DNS.query as query | where query!="unknown" | rex field=query "(?<domain>\w+\.\w+?)(?:$ |/)"] | makemv delim=" " answer | makemv delim=" " type | sort -count | table count,src,domain,type,query,current_answer,discovered_answer | makemv current_answer | mvexpand current_answer | makemv discovered_answer | eval n=mvfind(discovered_answer, current_answer) | where isnull(n) | `dns_record_changed_filter`
The SPL above uses the following Macros:
Note that dns_record_changed_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
The SPL above uses the following Lookups:
How To Implement
To successfully implement this search you will need to ensure that DNS data is populating the
Network_Resolution data model. It also requires that the
discover_dns_record lookup table be populated by the included support search “Discover DNS record”.
Splunk>Phantom Playbook Integration
If Splunk>Phantom is also configured in your environment, a Playbook called “DNS Hijack Enrichment” can be configured to run when any results are found by this detection search. The playbook takes in the DNS record changed and uses Geoip, whois, Censys and PassiveTotal to detect if DNS issuers changed. To use this integration, install the Phantom App for Splunk
https://splunkbase.splunk.com/app/3411/, add the correct hostname to the “Phantom Instance” field in the Adaptive Response Actions when configuring this detection search, and set the corresponding Playbook to active.
Known False Positives
Legitimate DNS changes can be detected in this search. Investigate, verify and update the list of provided current answers for the domains in question as appropriate.
Associated Analytic story
source | version: 3