Detection: Windows Set Custom DNS ServerLevelPlugin Via Dnscmd

Description

The following analytic detects command-line usage of dnscmd.exe to configure the Microsoft DNS ServerLevelPluginDll setting. This setting allows the DNS service to load an arbitrary DLL, which can be abused by attackers with DNS administrative privileges to execute code in the context of the DNS service. If confirmed malicious, this activity could enable persistence, privilege escalation, or domain controller compromise through malicious DLL loading.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5
 6from datamodel=Endpoint.Processes where
 7
 8Processes.process_name="dnscmd.exe"
 9Processes.process="*/config *"
10Processes.process="*/serverlevelplugindll *"
11
12by Processes.process Processes.vendor_product Processes.user_id Processes.process_hash
13   Processes.parent_process_name Processes.parent_process_exec Processes.action
14   Processes.dest Processes.process_current_directory Processes.process_path
15   Processes.process_integrity_level Processes.original_file_name Processes.parent_process
16   Processes.parent_process_path Processes.parent_process_guid Processes.parent_process_id
17   Processes.process_guid Processes.process_id Processes.user Processes.process_name
18
19
20| `drop_dm_object_name(Processes)`
21
22| `security_content_ctime(firstTime)`
23
24| `security_content_ctime(lastTime)`
25
26| `windows_set_custom_dns_serverlevelplugin_via_dnscmd_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	Other	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'XmlWinEventLog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'XmlWinEventLog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

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

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Legitimate administrative activities may involve dnscmd.exe usage or registry changes for DLL management in DNS servers. Filter alerts to exclude authorized administrative actions.

Associated Analytic Story

• Windows Persistence Techniques

Risk Based Analytics (RBA)

Risk Message:

Potential DNS ServerLevelPlugin DLL configuration observed on $dest$ via $process$.

References

• https://medium.com/@esnesenon/feature-not-bug-dnsadmin-to-dc-compromise-in-one-line-a0f779b8dc83

• https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/dnscmd

Detection Testing

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: 1