T1128.md

T1128 - Netsh Helper DLL

Description from ATT&CK

Netsh.exe (also referred to as Netshell) is a command-line scripting utility used to interact with the network configuration of a system. It contains functionality to add helper DLLs for extending functionality of the utility. (Citation: TechNet Netsh) The paths to registered netsh.exe helper DLLs are entered into the Windows Registry at HKLM\SOFTWARE\Microsoft\Netsh.

Adversaries can use netsh.exe with helper DLLs to proxy execution of arbitrary code in a persistent manner when netsh.exe is executed automatically with another Persistence technique or if other persistent software is present on the system that executes netsh.exe as part of its normal functionality. Examples include some VPN software that invoke netsh.exe. (Citation: Demaske Netsh Persistence)

Proof of concept code exists to load Cobalt Strike's payload using netsh.exe helper DLLs. (Citation: Github Netsh Helper CS Beacon)

Detection: It is likely unusual for netsh.exe to have any child processes in most environments. Monitor process executions and investigate any child processes spawned by netsh.exe for malicious behavior. Monitor the HKLM\SOFTWARE\Microsoft\Netsh registry key for any new or suspicious entries that do not correlate with known system files or benign software. (Citation: Demaske Netsh Persistence)

Platforms: Windows

Data Sources: Process monitoring, DLL monitoring, Windows Registry

Permissions Required: Administrator, SYSTEM

System Requirements: netsh

Contributors: Matthew Demaske, Adaptforward

Atomic Tests

• Atomic Test #1 - Netsh Helper DLL Registration

Atomic Test #1 - Netsh Helper DLL Registration

Netsh interacts with other operating system components using dynamic-link library (DLL) files

Supported Platforms: Windows

Inputs

Name	Description	Type	Default Value
helper_file	Path to DLL	Path	C:\Path\file.dll

Run it with command_prompt!

netsh.exe add helper #{helper_file}