Detection: Windows NirSoft Utilities

Description

The following analytic identifies the execution of commonly used NirSoft utilities on Windows systems. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution details such as process name, parent process, and command-line arguments. This activity is significant for a SOC because NirSoft utilities, while legitimate, can be used by adversaries for malicious purposes like credential theft or system reconnaissance. If confirmed malicious, this activity could lead to unauthorized access, data exfiltration, or further system compromise.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
 3as lastTime FROM datamodel=Endpoint.Processes
 4by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
 5   Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
 6   Processes.parent_process_name Processes.parent_process_path Processes.process
 7   Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id
 8   Processes.process_integrity_level Processes.process_name Processes.process_path
 9   Processes.user Processes.user_id Processes.vendor_product
10
11| `drop_dm_object_name("Processes")`
12
13| `security_content_ctime(firstTime)`
14
15| `security_content_ctime(lastTime)`
16
17| lookup update=true is_nirsoft_software filename as process_name OUTPUT nirsoftFile
18
19| search nirsoftFile=true
20
21| `windows_nirsoft_utilities_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

False positives may be present. Filtering may be required before setting to alert.

Associated Analytic Story

• Data Destruction

• WhisperGate

References

• https://www.cisa.gov/uscert/ncas/alerts/TA18-201A

• http://www.nirsoft.net/

• https://www.microsoft.com/security/blog/2022/01/15/destructive-malware-targeting-ukrainian-organizations/

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: 8