Potential Persistence Via Netsh Helper DLL

A Sigma rule for process creation on Windows, by Victor Sergeev, oscd.community.

medium 1 ATT&CK technique 1 program it names 2 everyday examples trip it

What it looks for

its detection, as SigmaHQ writes it

detection:
  selection_cli:
    CommandLine|contains|all:
      - 'add'
      - 'helper'
  selection_img:
    - OriginalFileName: 'netsh.exe'
    - Image|endswith: '\netsh.exe'
  condition: all of selection_*

The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by Victor Sergeev, oscd.community, under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.

Command lines that trip it

everyday examples from tldr-pages, CC BY 4.0, each read by CmdID

Add a helper Dynamic Link Library (DLL) on the page for netsh.exe

netsh add helper path\to\file.dllIdentify

To add a helper DLL located at C:\dlls\HelperDLL.dll, run the following command on the page for netsh add

netsh add helper C:\dlls\HelperDLL.dllIdentify

The commands LOLBAS or GTFOBins documents for netsh.exe trip it too: each is on its program’s page, read by CmdID.

Programs and files it names

their pages here

netsh.exe

ATT&CK

the techniques it is tagged with

T1546.007Event Triggered Execution: Netsh Helper DLL