T1564.003 - Hide Artifacts: Hidden Window

Description from ATT&CK

Adversaries may use hidden windows to conceal malicious activity from the plain sight of users. In some cases, windows that would typically be displayed when an application carries out an operation can be hidden. This may be utilized by system administrators to avoid disrupting user work environments when carrying out administrative tasks. Adversaries may abuse these functionalities to hide otherwise visible windows from users so as not to alert the user to adversary activity on the system.(Citation: Antiquated Mac Malware) On macOS, the configurations for how applications run are listed in property list (plist) files. One of the tags in these files can be apple.awt.UIElement, which allows for Java applications to prevent the application's icon from appearing in the Dock. A common use for this is when applications run in the system tray, but don't also want to show up in the Dock. Similarly, on Windows there are a variety of features in scripting languages, such as [PowerShell](https://attack.mitre.org/techniques/T1059/001), Jscript, and [Visual Basic](https://attack.mitre.org/techniques/T1059/005) to make windows hidden. One example of this is powershell.exe -WindowStyle Hidden.(Citation: PowerShell About 2019) In addition, Windows supports the `CreateDesktop()` API that can create a hidden desktop window with its own corresponding explorer.exe process.(Citation: Hidden VNC)(Citation: Anatomy of an hVNC Attack) All applications running on the hidden desktop window, such as a hidden VNC (hVNC) session,(Citation: Hidden VNC) will be invisible to other desktops windows.

Atomic Tests

• Atomic Test #1 - Hidden Window

• Atomic Test #2 - Headless Browser Accessing Mockbin

Atomic Test #1 - Hidden Window

Launch PowerShell with the “-WindowStyle Hidden” argument to conceal PowerShell windows by setting the WindowStyle parameter to hidden. Upon execution a hidden PowerShell window will launch calc.exe

Supported Platforms: Windows

auto_generated_guid: f151ee37-9e2b-47e6-80e4-550b9f999b7a

Inputs:

| Name | Description | Type | Default Value | |——|————-|——|—————| | powershell_command | Command to launch calc.exe from a hidden PowerShell Window | string | powershell.exe -WindowStyle hidden calc.exe|

Attack Commands: Run with

1	powershell

!

1
Start-Process #{powershell_command}

Atomic Test #2 - Headless Browser Accessing Mockbin

The following Atomic Red Team test leverages the Chrome headless browser to access a mockbin site. Create your own Mockbin.org site and replace the BIN in the inputs. The default Mockbin ID forwards to google.com and you may view the details here https://mockbin.org/bin/f6b9a876-a826-4ac0-83b8-639d6ad516ec/view. Reference: https://cert.gov.ua/article/5702579

Supported Platforms: Windows

auto_generated_guid: 0ad9ab92-c48c-4f08-9b20-9633277c4646

Inputs:

| Name | Description | Type | Default Value | |——|————-|——|—————| | bin_id | Mockbin.org BIN ID | string | f6b9a876-a826-4ac0-83b8-639d6ad516ec| | browser | Browser to use (msedge, chrome, firefox) | string | chrome|

Attack Commands: Run with

1	command_prompt

!

start "" #{browser} --headless --disable-gpu https://mockbin.org/bin/#{bin_id}

Cleanup Commands:

taskkill /im #{browser} /f