Event Triggered Execution: Netsh Helper DLL

Adversaries may establish persistence by executing malicious content triggered by Netsh Helper DLLs. 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. [1] The paths to registered netsh.exe helper DLLs are entered into the Windows Registry at HKLM\SOFTWARE\Microsoft\Netsh.

Adversaries can use netsh.exe helper DLLs to trigger execution of arbitrary code in a persistent manner. This execution would take place anytime netsh.exe is executed, which could happen automatically, with another persistence technique, or if other software (ex: VPN) is present on the system that executes netsh.exe as part of its normal functionality. [2][3]

ID: T1546.007
Sub-technique of:  T1546
Tactics: Privilege Escalation, Persistence
Platforms: Windows
Permissions Required: Administrator, SYSTEM
Data Sources: DLL monitoring, Process command-line parameters, Process monitoring, Windows Registry
Contributors: Matthew Demaske, Adaptforward
Version: 1.0
Created: 24 January 2020
Last Modified: 24 March 2020

Procedure Examples

Name Description
netsh

netsh can be used as a persistence proxy technique to execute a helper DLL when netsh.exe is executed.[3]

Mitigations

This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.

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. [3]

References