WARNING THIS IS A EXPERIMENTAL object

We have not been able to test, simulate, or build datasets for this object. Use at your own risk. This analytic is NOT supported.

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Description

This search looks for specific command-line arguments that may indicate the execution of tools made by Nirsoft, which are legitimate, but may be abused by attackers.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2020-07-21
  • Author: Bhavin Patel, Splunk
  • ID: 3d8d201c-aa03-422d-b0ee-2e5ecf9718c0

Annotations

ATT&CK
ID Technique Tactic
T1072 Software Deployment Tools Execution, Lateral Movement
Kill Chain Phase
  • Installation
  • Actions on Objectives
NIST
  • PR.IP
CIS20
  • CIS 3
CVE
1
2
3
4
5
6
| tstats `security_content_summariesonly` count min(_time) values(Processes.process) as process max(_time) as lastTime from datamodel=Endpoint.Processes where (Processes.process="* /stext *" OR Processes.process="* /scomma *" ) by Processes.parent_process Processes.process_name Processes.user 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
|`security_content_ctime(lastTime)` 
| `detection_of_tools_built_by_nirsoft_filter`

Macros

The SPL above uses the following Macros:

Note that detection_of_tools_built_by_nirsoft_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time
  • Processes.process
  • Processes.parent_process
  • Processes.process_name
  • Processes.user

How To Implement

You must be ingesting endpoint data that tracks process activity, including parent-child relationships from your endpoints to populate the Endpoint data model in the Processes node. The command-line arguments are mapped to the “process” field in the Endpoint data model.

Known False Positives

While legitimate, these NirSoft tools are prone to abuse. You should verfiy that the tool was used for a legitimate purpose.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
25.0 50 50 tbd

Reference

Test Dataset

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 | version: 3