Detection: Detect Remote Access Software Usage DNS

Updated Date: 2024-09-30 ID: a16b797d-e309-41bd-8ba0-5067dae2e4be Author: Steven Dick Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects DNS queries to domains associated with known remote access software such as AnyDesk, GoToMyPC, LogMeIn, and TeamViewer. This detection is crucial as adversaries often use these tools to maintain access and control over compromised environments. Identifying such behavior is vital for a Security Operations Center (SOC) because unauthorized remote access can lead to data breaches, ransomware attacks, and other severe impacts if these threats are not mitigated promptly.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime values(DNS.answer) as answer from datamodel=Network_Resolution by DNS.src DNS.query 
 3| `drop_dm_object_name("DNS")` 
 4| `security_content_ctime(firstTime)` 
 5| `security_content_ctime(lastTime)` 
 6| lookup remote_access_software remote_domain AS query OUTPUT isutility, description as signature, comment_reference as desc, category 
 7| eval dest = query 
 8| search isutility = True 
 9| `remote_access_software_usage_exceptions` 
10| `detect_remote_access_software_usage_dns_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 22	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`

Macros Used

Name	Value
remote_access_software_usage_exceptions	`eval exception_asset = CASE(isnotnull(src),src,isnotnull(dest),dest)
detect_remote_access_software_usage_dns_filter	`search *`

detect_remote_access_software_usage_dns_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
T1219	Remote Access Software	Command And Control

KillChainPhase.COMMAND_AND_CONTROL

NistCategory.DE_AE

Cis18Value.CIS_10

Akira

Carbanak

Cobalt Group

DarkVishnya

Evilnum

FIN7

GOLD SOUTHFIELD

INC Ransom

Kimsuky

MuddyWater

Mustang Panda

RTM

Sandworm Team

Scattered Spider

TeamTNT

Thrip

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 Risk Event	True

This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

To implement this search, you must ingest logs that contain the DNS query and the source of the query. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the DNS logs. The logs must also be mapped to the Network_Resolution data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process. The "exceptions" macro leverages both an Assets and Identities lookup, as well as a KVStore collection called "remote_software_exceptions" that lets you track and maintain device-based exceptions for this set of detections.

Known False Positives

It is possible that legitimate remote access software is used within the environment. Ensure that the lookup is reviewed and updated with any additional remote access software that is used within the environment. Known false positives can be added to the remote_access_software_usage_exception.csv lookup to globally suppress these situations across all remote access content

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
A domain for a known remote access software $query$ was contacted by $src$.	4	20	20

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

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`

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