Hidden Window
Where this stands
One published detection covers this technique. Every one is unverified — no rule on Siemphony has been executed against real telemetry.
What the technique is
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. 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, Jscript, and Visual Basic to make windows hidden. One example of this is powershell.exe -WindowStyle Hidden. The Windows Registry can also be edited to hide application windows from the current user. For example, by setting the WindowPosition subkey in the HKEY_CURRENT_USER\Console\%SystemRoot%_System32_WindowsPowerShell_v1.0_PowerShell.exe Registry key to a maximum value, PowerShell windows will open off screen and be hidden. […]
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN0360
Suspicious use of scripting parameters or registry edits to hide process windows (e.g., powershell.exe -WindowStyle Hidden, or registry modifications pushing window positions off screen). Defender view: correlation of hidden execution with anomalous process lineage or hVNC-like CreateDesktop API calls.
- AN0361
Suspicious invocation of GUI utilities or scripts with suppressed or redirected windowing options. Defender view: detection of X11 or Wayland calls to spawn windows that do not appear on active displays, or use of nohup/screen/tmux to mask interactive shells.
- AN0362
Modification of plist files to set apple.awt.UIElement or similar flags hiding app icons and windows, and dscl/command-line activity that suppresses visibility. Defender view: correlation of plist modifications with unexpected hidden user applications.
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