Modifying .lnk Shortcuts

This is a quick lab showing how .lnk (shortcut files) can be used for persistence.

Execution

Say, there's a shortcut on the compromised system for a program HxD64 as shown below:

. That shortcut can be hijacked and used for persistence. Let's change the shortcut's target to this simple powershell:

powershell.exe -c "invoke-item \\VBOXSVR\Tools\HxD\HxD64.exe; invoke-item c:\windows\system32\calc.exe"

It will launch the HxD64, but will also launch a program of our choice - a calc.exe in this case. Notice how the shortcut icon changed to powershell - that is expected:

We can change it back by clicking "Change Icon" and specifying the original .exe of HxD64.exe:

The original icon is now back:

Demo

Below shows the hijack demo in action:

In the above gif, we can see the black cmd prompt for a brief moment, however, it can be easily be hidden by changing the Run option of the shortcut to Minimized:

Running the demo again with the Run: Minimized shows the black prompt went away:

Note that hovering the shortcut reveals that the program to be launched is the powershell.

Reference

Boot or Logon Autostart Execution: Shortcut Modification, Sub-technique T1547.009 - Enterprise | MITRE ATT&CK®