Windows NirSoft Utilities

SPLUNK detection rule by Michael Haag, Splunk · Apache-2.0

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. Note that this search does not use a where clause to filter out known benign paths, as NirSoft utilities can be executed from various locations. This might hinder performance in environments with high data volumes. Apply additional filtering as necessary to enhance this.

name: Windows NirSoft Utilities
id: 5b2f4596-7d4c-11ec-88a7-acde48001122
version: 10
creation_date: '2022-01-24'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: Hunting
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.
    Note that this search does not use a where clause to filter out known benign paths, as NirSoft utilities can be executed from various locations. This might hinder performance in environments with high data volumes.
    Apply additional filtering as necessary to enhance this.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
    as lastTime FROM datamodel=Endpoint.Processes
    by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
       Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
       Processes.parent_process_name Processes.parent_process_path Processes.process
       Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id
       Processes.process_integrity_level Processes.process_name Processes.process_path
       Processes.user Processes.user_id Processes.vendor_product
    | `drop_dm_object_name("Processes")`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | lookup update=true is_nirsoft_software filename as process_name OUTPUT nirsoftFile
    | search nirsoftFile=true
    | `windows_nirsoft_utilities_filter`
how_to_implement: 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.
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/
analytic_story:
    - Data Destruction
    - WhisperGate
asset_type: Endpoint
mitre_attack_id:
    - T1588.002
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1588.002/atomic_red_team/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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7215d625-b6cb-4773-b33e-93280a3f1427

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