Detection: DNS record changed

DEPRECATED DETECTION

This detection has been marked as deprecated by the Splunk Threat Research team. This means that it will no longer be maintained or supported. If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2024-08-15 ID: 44d3a43e-dcd5-49f7-8356-5209bb369065 Author: Jose Hernandez, Splunk Type: TTP Product: Splunk Enterprise Security

Description

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.

 1
 2| inputlookup discovered_dns_records 
 3| rename answer as discovered_answer 
 4| join domain[
 5|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 
 6| rename DNS.query as query 
 7| where query!="unknown" 
 8| rex field=query "(?<domain>\w+\.\w+?)(?:$
 9|/)"] 
10| makemv delim=" " answer 
11|  makemv delim=" " type 
12| sort -count 
13| table count,src,domain,type,query,current_answer,discovered_answer 
14| makemv current_answer  
15| mvexpand current_answer 
16| makemv discovered_answer 
17| eval n=mvfind(discovered_answer, current_answer) 
18| where isnull(n) 
19| `dns_record_changed_filter`

Data Source

Name Platform Sourcetype Source Supported App
N/A N/A N/A N/A N/A

Macros Used

Name Value
security_content_summariesonly summariesonly=summariesonly_config allow_old_summaries=oldsummaries_config fillnull_value=fillnull_config``
dns_record_changed_filter search *
dns_record_changed_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1071.004 DNS Command And Control
KillChainPhase.COMMAND_AND_CONTROL
NistCategory.DE_CM
Cis18Value.CIS_13
APT18
APT39
APT41
Chimera
Cobalt Group
FIN7
Ke3chang
LazyScripter
OilRig
Tropic Trooper

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

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. (Playbook Link:https://my.phantom.us/4.2/playbook/dns-hijack-enrichment/)

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

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
tbd 25 50 50
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Not Applicable N/A N/A N/A
Unit ❌ Failing N/A N/A N/A
Integration ❌ Failing N/A N/A N/A

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 4